loneroad

iTrader: (3)

Im on a quest to make the most efficient 134 system for our cars.Something that anyone can do.I know very little about AC.I am learning as I go. I do have the basic tools ,guages and vac pump. Im looking at buying all new parts except for the accumulator and hoses, they will be flushed.
im going to be doing 2 cars at once.

the first camaro is a stock 91 305 tbi
the second is a 90 w/ a 383. both are using the serpentine belts.
Both cars are black convertibles and I live in Fla.
the stock 91 will be using the stock radiator and fan.
the 90 has a aftermarket radiator and dual fan.

Im trying to find all the info i can into making a 134 system work as efficiently as possible in these third gens.

Ive found cooltop 134a.
and using a vov orrifice tube.
and a parallel flow condensor.
weatherstripping around the edges of the condesor and radiator.

there isnt a bolt in condensor, thats where im getting stuck at the moment. finding a size that will fit and mouting shouldnt be a prob. its the hose ends that are slowing me down.

it looks like all the parellel condesors fittings come straight out.while my condensor fittings turns 90 degrees out. how hard would it be to make 2 adaptor hoses?

i might be looking at this wrong but it looks like you could take and cut the 90degree bends off of the old condensor, and flair the end with a new nut and connect.

ive found a ebay auction for a compressor kit:
http://cgi.ebay.com/ebaymotors/ws/eB...=STRK:MEWAX:IT

This should be a good start to my build.
I am in the reading and researching phase now. I only want to do this once.
I know there are some AC wizards here. Please share your wisdom.
Any info is appreciated. hopefully by the end of this we will all have a parts list to go by:

battman

iTrader: (2)

From my experience with R134 in the the stock system the best thing that can be done is to upgrade the cooling fans. My 92 would only marginally cool at idle in the hot summer with stock fans, I upgraded to dual lt1 fans and it cools as good idling as it does going down the road with the stock condenser.

Blind Driver

R12 is the most efficient and still available.

loneroad

iTrader: (3)

R12 cant be bought without a license, or going to a shop. Not the point of the thread.

Fast355

iTrader: (2)

x100....I like my air colder than R12 can even make.

R134a in a system that was designed for R134a I don't even find adequate.

transam85dudeman

at swap meets, flee markets, mexicans typically will sell you as many cans of r12 you need. ive seen them many times. CANS! not r134, but r12!! you do need a license to handle r12 and to buy it, but these are mexicans, economy is shot, they need funds,, im converting to r134, better money wise... but i heard if you use a ford orffice tube its better cooling.

knapper79

First off, you cannot flush an accumulator, or reciever/dryer for that matter. They have desiccant bags in them that will be ruined. Always replace an accumulator or reciever/dryer anytime your system has been open (or just completely drained) for any length of time. ALWAYS replace accum. or r/d when retrofitting.
Secondly, all evaps, most hoses, and condensors are compatible with either R12 or 134a. Most compressors are as well. On those year vehicles, they are. The oil is not cross compatible and R12 o-rings do not work in 134a systems, but 134a o-rings work in R12 systems.
Never cut and flare a/c components. I have seen people do this then wonder why their system won't hold pressure. There are ways to make adapters. My recommended method would be to purchase the appropriate fittings and hose length/diameter to make an adapter hose from a place like this http://www.nostalgicairparts.com/ac/...ose-kits-7.php or any similar. These fittings have to be crimped on. If you plan on doing a lot of these jobs you may benefit from buying the crimping tool. If not, take your hoses that you put together with fittings to a hydraulic shop and ask them to crimp for you. Most places will do it for very little money. You cannot crimp these fitting any other way (i.e. pliers, bench vice, etc) they will not hold. Don't forget, the high side of you a/c system can get up to 300 psi under heavy load in hot weather.
R134a systems (especially on retrofit jobs) require a little more oil than standard R12 systems. There are retrofit tables out there that will even tell you how much to add. R12 oil (if originally ester, is not compatible with 134 systems) If you can not find a number, I typically put in 1.25 times as much PAG 134a oil in a retrofit than is called for in the original R12 setup. Remember, more oil means less refridgerant is added.
Lastly, always remember that R134a is very different than R12. It cools very effectively when the system is designed to do it. In a R12 system, you could always add just a few more ounces to make the system cool just a bit more. However, you can not do this in a 134a system, it will actually not cool as well if you add to much. Again, there are charts that will tell you how much 134a to put in as a retrofit. In absence of charts, I use a specific method developed from over 15 years of diong A/C service that is virtually impossible to explain in less than a 30 page thesis (sorry to lazy to type that much on here). But basically the charge will be 80-90% of what you would have charged if using R12. That will get you close, then performance testing the system (and maybe trial and error depending on your A/C skill level) will get you much closer to perfect.
Always make sure you completely evac the system to -30 PSI (if your pump is capable), keep it pulling once it gets to that reading for at least 5 minutes, then turn off pump, let sit for 30-60 minutes and make sure it is still holding vacuum.
If you have an electronic fan, wire in a relay to turn on the fan when the A/C system is turned on (really only applies if you car was originally equiped with mechanical fans).
This should basically get you were you need to be.
Of course if you are ever in the Huntsville, AL area, look me up. I have a crap load of 134a that I would love to get rid of for cost.

Fast355

iTrader: (2)

R134a SUCKS period...STAY AWAY FROM IT....Even in a system designed to use it, it is slow to pull down cold on initial startup and doesn't stay cold at idle. It also LEAKS very easily out of the system, even systems that are "TIGHT" can lose 1/2 lb a year. My 2006 Dodge Ram wouldn't even get below 60* driving on the highway in 100*F weather. In fact I have NEVER driven a R134a vehicle thats a/c blew cold enough for me to go WOW this is cold.

Go online and take one of the ASE Certification tests for Refrigerants.. Pay the $20 and buy R12 legally.... Then you can charge your car and enjoy ICE cold air. I can get R12 cheaply here.

I "FIX" the a/c on all my vehicles and it makes them a joy to drive in our heat waves.

knapper79

I hate to say this, but R134a does not "suck period". If your system was designed to run it, and it is not cooling enough, your system sucks... not the refrigderant used in it.

Most people do not truly understand A/C principles. R12 and R134a operate under the same thermodynamic principles, just as any refridgerant does. The two main principles at play for any A/C system are 1) the latent heat of condensation and 2) the latent heat of evaporation.

Without getting into a long drawn out explanation that is really beyond the scope of this argument, I will explain how the A/C system works in very basic terms and ideas so that all can understand it. The bottom line is that an A/c systems efficeincy is a direct result of the pressure the system is operating at. In order to fully understand how an A/C system works you must understand the basic characteristic of any refridgerant. That characteristic is simply - a refridgerants temperature that it evaporates (boils) or condenses (changes from gas to liquid) is in direct relationship to its pressure.

For an A/C system to operate very well, all the components must be operating properly to do the following process.
1) the compressor must be able to take a refridgerant (in gas form) at ambient pressure and compress it, thereby raising the pressure. Raising the pressure also raises the bowling point.
2) the condensor takes this high pressure gas and cools it slightly, turning it into a high pressure liquid. In other words, the cooler air passing over the condensor with a hot, high pressure gas lowers the temperature slightly converting the gas to liquid at roughly the same pressure. - latent heat of condensation -
3) The high pressure liquid then travels to a pressure changing device (orifice tube or expansion valve) thereby lowing the pressure on the output side of said device. In other words, the orifice tube (or expansion valve) takes the high pressure liquid (typically somewhere between 180-250 psi depending on your system) and drop the pressure to an ideal lower pressure for evaporation (or boiling). The "ideal" pressure is typically just above 32 degrees or else the moisture in the air would freeze to you evaporator and reduce total air flow across it.
3) The evaporator allows warm air to pass over it. The heat in the air evaporates (boils) the liquid refridgerant, converting it into a gas again. The heat in the air is transferred to the refridgerant. In effect, the boiling action of the refridgerant reduces the temperatue of the air passing over the evaporator. - latent heat of evaporation - this cooler air is what you feel blowing out of the vents.
4) the refridgerant then eits the evaporator as a cold, low (or ambient) presure gas and returns to the compressor to start the cycle all over again.

Now none of the explains why R12 and R134a or comparable as refridgerants unless you understand the laws of physics surrounding the above mentioned principles. Once those laws are understood, you know that regardless of using R12, R134a, or any other chemical composition of refridgerant, the ability of it to cool is based solely on the pressure drop capable at the orifice tube or expansion valve. So any refridgerant that is exiting the orifice tube or ev at (let's say) 30 psi, will boil at the same temperature, and the heat exchange will be roughly the same. Both will cool the air at the same rate given the same temperatures.

Now in a retrofit system it is important to realize that R134a is slightly more dense thatn R12. This is why a R134a system operates better with cross flow condensor and evaporator. In an original system, this is not a factor at all. So if your vehicle originally equiped with R134a is not cooling to what it should, its because the system is failing somewhere, not because the type of refridgerant.

You also have to remember that the output of an A/C system has many variables that effect its cooling effect. The biggest one is the climate it is operating at. A system running with an outside temperate of 70 degrees and less than 50% humidity should blow air as cold as 36 degrees easily. that same system operating in 100 degrees and 90% humidity may only blow air out at 60 degrees. Thats a significant difference, but does not mean that the system is not working.

Lastly, R134a does not leak at any rate higher than R12. If your system is losing R134 on a regular basis it is because you have a small leak in your system, not because of the refridgerant. The most common areas for a slow leak to occur are o-rings, expansion valve gaskets, and schrader valves in your service ports.

Bottom line up front - an A/C system only works as well as the components that operate it given the environment it is working in and really has almost nothing to do with the type of refridgerant it uses.

Fast355

iTrader: (2)

You just put out ALOT of mis-information in your post.....There are some additional physics lessons you need to learn... You also need to realize that different refrigerants have different LATENT HEAT CAPACITIES as well as different THERMAL CONDUCTIVITIES. Both of these GREATLY effect the efficiency of the refrigerant. Not to mention LATENT HEAT OF VAPORIZATION and LATENT HEAT of CONDENSATION, ARE DIFFERENT for DIFFERENT refrigerants. What thise means is that some refrigerants store and release heat better than others. It is also worth noting that each refrigerant has its own pressure/temperature curve. So R12 at 30 PSI WILL GET COLDER than R134a at 30 PSI. The pressure/temperature curve effects the ability for the refrigerant to transfer heat.

Here is my explination on this....IN a PERFECT WORLD environment, both systems running the same pressure, same heat load, etc. Lets say the high side is 250 psi, low side 35 psi....Each refrigerant would give a different temperature in the evaporator and condensor for the same pressures.

Temp of-------R-134a----------R12
Condensor----146.30*F-------155.95*F
Evaporator-----39.96*F-------32.15*F

Now raise the pressures up to a high side of 300 psi and a low side of 50 psi (My 1997 Chevy Express van runs this in 105*F, 70% humidity day and it has MOST EVERY TRICK DONE TO IT, INCLUDING late model 2006 Chevrolet E-Fans)

Temp of-------R-134a----------R12
Condensor----162.98*F--------173.79*F
Evaporator-----53.98*F--------52.59*F

What will actually happen in a system that is operation the condensor will reject the same amount of heat and the R12 systems head pressure will be lower...Reducing the head pressure has the effect of reducing the evaporator pressure. Reducing the evaporator pressure, reduces its temperature and will give colder air from the vents.

What you have to understand also is that as the pressures rise the R134a is not able to generate as much heat in the condersor and the ability for heat transfer is reduced compared to other "HOTTER" refrigerants.


I really don't care what you say about R134a being a "GOOD" refrigerant...It is NOT... IT SUCKS... I cannot believe that they actually allow refrigeration equipment containing it to be labeled "ENERGY STAR". The same system with a more efficient refrigerant will be more efficient and move more heat... PERIOD...

For example take PROPANE.... HC290 is a GREAT refrigerant, VERY efficient and capable of moving ALOT more heat than R134a or even R12 in the same system.

R134a has a smaller molecule and is more leak prone than other choices. In fact it will go right through a non-barrier hose (most 3rd gens).

knapper79

Fast355-

You are right.

However, for the sake of this thread, I tried to keep it as simple and basic as possible without comparing all refridgerant thermal values. the fact is that R12 and R134a values are within 3 degrees latent heat of each between the pressures of 0-85 psi (would hope low pressure side of any A/C system is operating within this range). And their thermal conductivities are very similar. That is one of the main reasons why R134a was chosen as a environmentally friendly replacement for R12.

I am really sorry you have not had good experience with R134a. I have retrofitted over 150 vehicles with R134a and had as good of performance as the original R12 system had. Admittedly, never retrofitted a 3rd Gen. the non-barrier hose is an issue. But aside from that, if all components are compatible with R134a, there should be no regular loss of refridgerant at all in the system.

So I guess it boils down to you think it sucks. I ,on the other hand, have been fortunate enough to work enough with A/C systems to know its not.

We can always agree to disagree.
Cheers!

Fast355

iTrader: (2)

I think ALOT of it has to do with location that I am in.... R134a systems just don't cool here. I have worked at several dealerships and driven so many new cars its not funny. I have been a service writer a few times too and lack of a/c performance is a very common issue. I have NEVER felt comfortable in one when it is 105*F outside, we probably have 30+ days a year over 100*F and any humidity at all. On the other hand both my Dodge Ram and Chevy Van have ICE cold air, but they are both Hydrocarbon blends.

loneroad

iTrader: (3)

you all have far more experience than me. If i put the following components together, I should be able to get into the low ,dry 30's right? If I could get it any colder than that the system would freeze up right? heres the list and websites:

Ice32
http://www.ice32.com/index.htm
cooltop
http://refrigerantsales.net/shop/info/cooltop.html
parallel condenser
https://www.ackits.com/pc/12-0568A/P...15.5+X+30.5%29
And the V.O.V
http://www.ackits.com/merchant.mvc?S...&Category_Code=

KITT1983

iTrader: (3)

any updates?

ikeepitreelz

Getting my new compressor,orifice tube and accumulator tomorrow, any suggestions?

Keoman

iTrader: (3)

Thanks Knapper79 and fast355,
I learned more about AC systems in like 10 minutes than I have in my entire existance. But i guess we only care when it starts to effect us right?
Great Info here.
Kitt, UPDATE!

TTOP350

iTrader: (8)

My 2 cents.. Im not a A/C tech at all buuut 134 sucks, even in the new cars I have with a system designed 4 it.
My trusty old R12 systems cool faster longer and waaay more consistently esp at lower rpm.
Id honestly say stay away from 134, pay the money 4 R12 or go to any other country in the world where R12 is still used/sold and buy a butt load of it for a buck a pound..

Fast355

iTrader: (2)

I agree with you with only 1 exception. I was having trouble with freezing the evaporators up on the 97 Express Conversion Van with a huge aftermarket rear a/c unit. and switched it back to R134a. Just went on vacation in it from Dallas to Galveston Texas in 100+ heat and stupid amounts of humidity. It would cool down within 10-15 miles on the highway and after less than 1 hour it would be so cool in the van we were turning down the blower. My 6 year old neice had a heavy blanket on and was freezing. On the highway with both a/c units on high blower, the front was blowing 37*F air out of the vents. We eventually turned the blowers to nearly their lowest settings and turned off the recirculate we were so cool.

loneroad

iTrader: (3)

bring on the i told you so's

i replaced everything. i upgraded to a p-flow condenser. put in new cooling fans. Added the ice 32 and used cooltop. and i got some advice from reid. and all was good till the dog days of summer hit.

IF.... i had a white hardtop with tinted windows this setup might do well.

the heat just punishes my black verts,

Im going back to square one, and flush everything out, take the test and put autofrost in.

1982Z28Modified

Wow... a lot of misinformation laid out as science in this thread. Sorry it's so ****ing hot in Texas. God just wanted to see if idiots would live in an oven.


Now for the real provoking idea... R134a is just as good as R12. Buying anything other than a approved refrigerant is a waste of money. Freeze 12 and other crap sold is just a waste of money.


What most people don't understand is you have to change the pressure switch timing when the compressor cycles off and on. If you don't change that, then your retrofit will be a failure. R134 an R12 operate at two different pressures. Unless you adjust the switch, you will be short cycling the compressor and you will never get it cold enough for Florida or Texas.

Fast355

iTrader: (2)

As far as Galveston/Houston being hot and humid, it can be in the 90s and because of the humidity feel well over 100*F even in May/June. In fact I just looked up the weather there this very moment. 87*F, 69% humiditiy, 15 mph wind, and a real feel of 98*F. Here in the zip code I am standing it is 92*F, 42% humidity, 17 mph wind, and 95*F real feel. So yes it can get very warm and the humidity makes a vehicle a/c system struggle to cool.

You are an idiot if you honestly believe R134a to be just as good as R12. An "approved" refrigerant, once again sounds like a conformist idiot. There are refrigerants out there that work at a lower pressure than R134a and offer vastly improved cooling. R152a is one of them. Hydrocarbon blends are also GREAT refrigerants. They can

As for your cycling switch comment. That is true going down the highway at higher rpm with good airflow across the condenser, but as soon as you stop in bumper to bumper traffic on a really hot day, you will be blowing slightly cool/lukewarm air if you are running R134a regardless of how that switch is adjusted.

1982Z28Modified

Well Fast, sorry you can't get you a/c working properly. Take it to a professional. I don't live in God's oven, Texas, or God's waiting room, Florida. But it get's plenty hot up her in Detroit. Plenty of days in the 90's with humidity 70+.


First off, install a Variable Orifice Tube in your system. Delco part # 15-50122. Shop around... it's $30. Next install a new cycling switch Delco part # 15-2151. $15.


After having fully cleaned and flushed the system, installed the new parts and properly charged the system, set the cycling pressure. The old R12 systems cycled between 31-34psi. The R134 needs to cycle at 27-30psi. If you don't adjust the switch, the R134 will never perform like it should.


BTW Fast, the a/c system cycles on and off continuously, as it's designed to do. Only an old R12 system with a TXV runs continuously. Detroit stopped using those in the 70's.


The advantages of using a VOT or VOV (variable orifice tube or valve) is that it balances out the pressure at lower engine speeds. Or more simply, it cools more effectively at lower (idle) speeds.


Also I would get new hoses and a new compressor. Get a delco compressor. I have heard the quality of Four Seasons is not that great.


Like I said Fast, if you can't do the job, hire a professional.

mk1431

run 80 percent of recommened volume

Fast355

iTrader: (2)

My a/c blows ICE cold. So cold it fogs the outside of the windows up in 90+ weather if you keep it cranked up. Its R134a PERIOD!!!! System works fine once I removed that crap. I even took R134a out of my brand new Titan and swapped it to R152a. When your first started the truck it would blow cold air in about 1/2 the time and the a/c would bring down those 140*F interiors temps really quickly. By the time you rolled the windows down and released the heat wve inside it was ICE cold. It would hit 30-32*F out of the vents with the blower speed on high before the BCM would cycle the compressor. That still had a proper expansion valve in it, like my rear unit in my Express does.

Suction side pressure on a hot day with a dual evaporator at idle will be in the 45-60 psi range and air will blow about 60-65*F at idle. Don't care what vehicle you a driving.

90s is a LONG way from 104-110*F when it comes to cooling a vehicle, idling, stuck in a traffic jam, shortly after the vehicle was started. R134a just cannot move the heat as well as other refrigerants.

I cycle around 22-26 psi, whatever I can get away withour freezing up the evaporator. However that adjustment does NOTHING for idle cooling on a hot day with the blower cranked up to high.

1982Z28Modified

Well Fast... time to pull out the big gun. Do you work for the Big 3? Ford, GM, or Mopar?
No? I didn't think so. Well I work for Ford. 20 years now. Did you know that there is a test track in the Arizona desert at Whittman, where they do all hot weather testing. Every vehicle model is tested in extreme weather for years. R134a has been in Big 3 vehicles for 20+ years and it works just fine in Texas, Michigan, Alaska, and Florida. If your car doesn't cool you enough I suspect you don't know what your doing.


I said it before. Hire a licensed professional, not some Jose you find at the swap meet with a supply of R12.

Fast355

iTrader: (2)

I love how you don't know that I have my certifications in a/c and numerous areas of a vehicle. I have 10+ years of experience in the automotive repair field as well.

The Arizona reference really is not all that attention grabbing to me. The desert is DRY heat and less humidity = better cooling and lower temperatures.

I have done tons of experimenting with my personal vehicles and have figured out that regardless what the fender badge may have on it, they cool better once the R134a is removed and a better refrigerant is inserted. Same untouched system!

There is ABSOLUTELY NOTHING WRONG WITH MY A/C UNIT OTHER THAN THE CRAPPY R134a REFRIGERANT IT CONTAINED. At lunch it was blowing 38*F with the blower fans on high, idling in traffic. I have been around plenty of R134a vehicles and work for a Nissan dealership. We have numerous customers that complain of poor a/c performance and longer cool down times when the temperatures hit the triple digits. In the shade of the shop on a 105*F day keep in mind the OEMs say 60-65* vent temps depending on humidity are acceptable. That is marginal at best and a reflection of R134a refrigerants inability to reject heat.

The 97 Express van has a mixture of components in it that work well for me. I rebuilt the system a few years ago and it functions remarkeably well.

Aftermarket Sanden style compressor (Factory HD6 units SUCK and constantly leak at the case o-ring)
Duramax fan blade on a Trailblazer SS fan clutch
Flushed/Cleaned/Straightened factory condenser
New front evaporator 2 years ago (had a leak)
Ford Red .062" orifice tube
New R134a rear expansion valve
Charged with R152a, approximately 60-65% of R134a charge
Converted from a non-adjustable to an adjustable cycling switch (1995 G30), ended up set at 32 psi cut-out
GMT400 10" pusher fan mounted in front of condenser controlled by the PCMs auxiliary fan output

The setup works so well that even changing to a 25% underdriven crank pulley barely effected the idle cooling.

EDIT- YOUR ARROGANCE FURTHER REMINDS ME OF WHY I WILL NEVER OWN A FORD OR ANOTHER BIG 3 VEHICLE.

I plan to stick with my Nissans.

I still laugh about the first night I drove my 2014 Pro4x Titan off the lot and ran an Ecoboost out of the light with less than 50 miles on the odometer of the Titan. He was more than a little pissed that a domestically built import outran his $50K truck.

Fast355

iTrader: (2)

I also laugh that a POS variable orifice was suggested. That is the quickest way to need to buy an evaporator when that thing snaps in half and cannot be retieved out of the inlet pipe. Have experience that first hand on a 02ish Tahoe. Some previous shop had tried to use one and the truck stopped cooling one day. It had snapped in half and wedged itself into the evaporator inlet. Ended up requiring an evaporator replacement to fix it.

Just thought I would show a few results.

deadbird

Arguing coldest and comfortable is a matter personal preference.

As of his posting time, it's 84°f and 73% humidity (9:14pm) in SoIN. My Xtreme(!) reaches 38°f even in sunny hours. It's cold enough for me to blend the hot/cold door to make it comfortable while driving after the cabin acclimates. In my work van, I'm thrilled if i can just be less humid..(80%+ is pretty normal humidity here even during 95°f+ full summer days)

This, to me, works great. To someone else who isn't subjected to working in gastly temps for a profession all day, might suck.

It's a matter of perception guys. Share info instead of a pissing contest. (Directed at no one specific)
Keep in mind, this is a 3rdgen topic, other cars are irrelevant unless you have a way to retrofit...

Alice89

iTrader: (6)

So I'm an idiot since I live in Texas?

You bumped a 4 year old thread to put forth your bigoted opinion. Enough said.

Oh and fast, r134a does not "suck period". It works just fine in all of my vehicles... and I live in "gods oven".

Fast355

iTrader: (2)

Actually once you have sone seat time with a vehicle that has a better refrigerant in it, R134a just can't do the job. I like sitting in air that is coming out so cold your knuckles start to hurt and fingers start tingling on a 105*F afternoon.

formula1LE

iTrader: (3)

Lol....this thread has made my day!

Elthesh

r134 in my system and the air comes out ice cold. It's so cold, I have to direct the air away from my hands or they freeze. I'm in an insanely humid area and its routinely in the 90s. I didn't notice a bit of difference between r12 and r134. Both were just as icy. It's also not leaked in the 8 years or so since the system was last open when the compressor was replaced. Also, the car is black on black on black. Every last thing in the car is black so, heat magnet and it still freezes.

I also had the same experience in my 79 TA. r12 to r134 and it was also just as icy.

formula1LE

iTrader: (3)

The biggest benefit one can do on R-134 retro-fits is to improve heat transfer by going with much higher capacity fans to pull more heat out of the condensor. For this season alone I don't dare for stock TPI fans....they just don't compare to 4th gen fan assemblies among others. Lack of heat removal on the liquid line leads to high head pressures which aid in lackluster cooling. I've never had any problems with R-134 and I have quite a bit of experience with it both in factory filled systems as well as retro-fits.

Fast355

iTrader: (2)

It really doesn't matter what you have for a fan in 100*F and above weather R134a =lackluster cooling to me. I have had the massive 2010ish Tahoe E-fans for a 34" wide radiator and R134a still sucked.

Fast355

iTrader: (2)

90s is not 100*+ in the shade with ambients over the hot asphalt of 115*F and beyond.

My last 3 trucks were black and the last was black on black leather. F-car also does not have the interior volume of a fullsize crew cab truck or van either.

Reid Fleming

iTrader: (2)

How have I missed this thread?

The argument about good air conditioning vs great air conditioning really does come down to climate. It's the same way with all season tires vs winter tires. People who live in flat places where it snows for 3 days and then melts will say that there is no difference between the two types of tires. But people who live in climates where it snows for months on end and/or live in mountainous areas will say that winter tires hands down are the better tires.

In terms of A/C, I'll admit that R-134a does the job well in northern climates. The heat load is much less and the humidity is lower too. So R-134a doesn't max out as easily as it does down in the humid south. Part of my issue with poor factory A/C is that most factories are based in northern climates or areas that don't see never ending summer heat and humidity. Arizona test track? I bet the testing consists of driving on an empty race track or some sort of long distance highway test. I'd be surprised if testing consisted of sitting in Phoenix traffic at 5PM rush hour.

But getting back to refrigerants. R-134a is like a fat man. R-12 is like a skinny man. The fat man has to sweat more while simultaneously cooling less. The physics of humans exhausting heat to the ambient by sweating are much the same as the physics of air conditioning exhausting heat to the ambient through the condenser. Again, the fat man living in Seattle doesn't have much of a hassle in the summertime. The fat man living in Houston is going to be miserably hot every time he steps outside.


The above psi points may be true for Ford, but they are incorrect for GM. The common R4 cycling compressors in GM vehicles (like ours) cycle at 25 psi (R-12). A common modification is to either adjust them (if possible) or replace with a 22 psi (R-134a) low pressure cycle switch. The variable displacement compressors like the V5 reduce their output when you reach 28 psi.

Reducing the output at 28 psi on a variable displacement (non-cycling) compressor makes sense. Because at 28 psi, you're getting 42° duct temps (with R-134a) with the evaporator running near 32°. No icing will happen. In summertime here, you won't reach 28 psi with R-134a. So the compressor runs full blast non-stop.

Simply replacing a 25 psi cycle off with a 22 psi cycle off works fine for air conditioning during spring/fall in Texas. But makes zero difference during the summertime. You're not going to get to 25 psi never mind 22 psi. The system will run non-stop and never cycle, because best case scenario is you're going to be hovering on 30 psi on the open freeway during the afternoon with no traffic. I've seen our Blazer blow 45° out the ducts for a hour straight on the highway during 95° weather. That's 30 psi. This was with the stock R-134a factory system.

Manufacturers have upped their game to make up for the poor performance of R-134a. New cars have bigger condensers, better condensers (parallel flow instead of tube and fin like our cars), faster and louder radiator fans (you can easily hear a Honda Civic radiator fan cycle on and off from 50 feet away), faster cabin blower speeds, non-tinted glass that has solar film built in. (Our 2002 Blazer has 70% un-tinted front door windows. The GTA is 85% in un-tinted form). New cars also have much more insulation than older cars. I've driven a Lincoln Town Car. And the temperature of the air isn't particularly cold, but the inside cabin feeling is very nice because it has massive insulation keeping the heat out in the first place. I'm not so lucky with my black GTA with black leather seats.

The phrase "ice cold" is thrown around way too often. I read a person say their A/C was "ice cold." This was after he measured the duct temp at 57°. That's beyond lame. You really need to throw a temp probe in your A/C vent and measure to see what ice cold is.

At 37° duct temps with R-134a in the summertime, I'd be happily surprised. With R-12, it would be running as it should. With R-406a (what I run), I'd be looking for a problem. That would be too warm. I routinely run my car at 31° duct temps. For an hour straight on the highway. Evaporator is running in the low 20's. Freeze up? Never. The system cycles off at 31°. Since the cycling compressor doesn't turn back on until 45 psi (aprox 42° evap temp), any trace ice amounts vanish. But I don't see any change in duct temp. Maybe a 1 degree temp rise to 32° in duct output when it cycles off. My digital probe has a decimal point, so I can see a 1/2 degree rise in temp even though there is no perceptible change in feel.

Getting back to R-134a. I know why the manufacturers went with it. It's easy to top up (being a single refrigerant). It never ices up the evaporator. And not a single case of it being brought back to the dealer with a customer complaint of it being too cold. Now back in the early 1990's when the R-12 --> R-134a conversions were first happening. And the original factory R-134a cars were hitting the market, there were plenty of complaints about R-134a being a lame refrigerant. But enough time has gone by that most of those R-12 cars were long ago converted/crushed/or simply left with non-functioning A/C (common if you live in a mild summer climate like Seattle or Vancouver. Why pay $800 to convert when summertime is 80°/30% humidity? Just deal with the heat for that week or so before it cools back down into the 70's during the daytime). People like us with 3rd gens, particularly in the south, are pretty much the only people still running R-12. The manufactures for the most part have upped the performance of everything else (condenser, fans, insulation, etc) that new vehicles aren't as problematic. The actual R-134a refrigerant is still the same as ever. Another thing that you don't suffer from with R-134a is fogging up the outside of the windshield. I do that quite frequently with R-406a. A quick turn on of the windshield wipers will clear the condensation. Or simply switch it from A/C to VENT and allow the interior temps to rise up enough that the condensation disappears.

But...

Getting to Fast355's point, I wholeheartedly agree that once you've tried something more high performance than R-134a, you'll never want to use R-134a again. The colder temp, the faster initial pull down (an underrated perk), and the increase in humidity removal are addicting. Spending the long summers here while feeling continually hot gets annoying. When it hasn't been below 70° inside or outside, daytime or night time, for several months, you don't want something that just barely cools you. You want something that makes you feel too cold while wearing a suit and driving at 4PM in the sunlight. When I drive my car, once the duct temps cross 35° and continue getting colder, there is a difference in feel. You can take a deep breath and feel the thickness of refreshing air through your entire body, much like you do when you step outside and take a deep breath when it's near freezing outside in winter. The humidity goes from manageable to gone. And your body changes from cool enough to wow this is comfortable.

I suppose you could equate R-134a cooling like you could using the heater in your car during wintertime with a 180° thermostat vs a 195° thermostat. With the 180 stat, it's "acceptable." But with the 195 stat, it's "hot."

Reid Fleming

iTrader: (2)

The Blazer has some advantages over the GTA.
1) Higher off the ground. Less concrete/black top radiating into the condenser and floor pan
2) Parallel flow condenser
3) Gargantuan two speed radiator fan that runs continuous all year regardless of if the A/C is turns on or not.
4) Shroud that keeps the fans blowing directly into the condenser/radiator
5) Factory tinted back seat and rear windows
6) Solar front seat 70% windows (vs 85% in the GTA)
7) Grey cloth interior (instead of black leather)

I remember the day I drove out to get a new windshield in the GTA. My appointment time was 2PM. It was 107° that day. Houston's all time heat record is only 109°. The high dew points here prevent the temperature from getting too high. We only get on average about 2-3 100 degree days per year. Dallas is a 3.5 hour drive north on the highway. But they get way more 100 degree days because their dew points are lower......Anyways, the drive out to the glass shop in the GTA was nice. Cold air the entire drive. When I got to the shop, the waiting room was 76° on the digital thermostat. (A/C on of course). By the time I left, it had gone up to 79° in there. The drive home was pleasant. I was pulling about 33° duct temps the entire way. I got home and parked the car. Let the glue dry. And got into the Blazer to grab some dinner. That was the only time I'd ever heard the radiator fan stay in high speed mode. It normally runs in high speed mode for the first 20 seconds when you start it up and then settles in low speed mode until you shut the engine off. But even with Cool Top in the Blazer (which works better than R-134a), it still wasn't anywhere as nice as the GTA in terms of comfort. Didn't matter what you had the cabin fan speed set on.

Driving with 100% R-134a in the Blazer would have been ugly.

Reid Fleming

iTrader: (2)

I filmed these a few years back. You just can't do this on R-134a.

(driving down the road)

(drain after parking the car) The line of water that follows me to my parking spot is hilariously visible.

15 minutes later....

Fast355

iTrader: (2)

^^^^^ You guys just don't understand until you have had the blower cranked up on high and seen vent temps into the mid to low 30s. I have seen my accumulator starting to pickup ice on a 95*F day when poking around under the hood with the blower motors cranked to high speeds.



My A/c also has a tendency to fog up the outside of all the windows when stopping in bumper to bumper traffic in the evenings. I also have a tendency to freeze my passengers out, because I like it so cold.

I was poking around in my a/c vents with my infared thermometer and something was at 9*F the other day!

formula1LE

iTrader: (3)

I must admit I don't mind the R-134 interior temps....regularly high 30's vent temps in my DD 05 Yukon Denali on a 95F day but man, that'd be killer to see vent temps as low as single digits! I wouldn't want to ever get out of my car! Hell, I'd be mad my car gets colder than my home AC unit! Lol....I may have to try the 406A just for the hell of it....

1982Z28Modified

Well Fast... You claim to be an expert. Maybe the Big 3 will hire you as a consultant! Of course they won't deal in brown market R12. Don't quit your day job.


And your comment about the VOV didn't make sense. It works fine in my Z28. That why I got a high quality AC Delco part.


R152a performs 11% better than R134a depending on conditions. I found this in a GM study about replacements for R134a done in 1999. I can upload the study if you like to read boring science. Here's the problem Fast. They don't sell 152 at the auto parts store. Such a pity.


And for those who question the cycling PSI... it was a standard GM R12 31-34psi. R134 is 27-30psi. These PSI gives you 32 degrees at the evap.


And Fast... if your accumulator is frosting up, your system is not right. But your an expert and know this.

Fast355

iTrader: (2)

Absolutely nothing wrong with an accumulator that gets a little frosty before the compressor cycles.If it doesn't get a little icy, you are giving up a few degrees of vent temps.

That Delco "high quality" part is still made as cheaply as possible in Mexico, Taiwan or China and therefore pretty crappy but don't get me started on the parts outsourcing of the "Big 3" that my tax money helped bail out 2/3s of!

You can pick up R152a at just about any groccery store, including Walmart and it is cheaper than R134a at the parts house by far!!! 11% is HUGE in a hot/humid climate especially in a congested traffic area where your system is already limping along at 1/2 its rated BTUs because the engine is at idle or slow engine speeds with minimal ram air across the condenser. It als9 makes a noticeable difference in compressor run time on moderate weather days and that means less overall HP draw and better fuel economy! Oh and like I said no reason to even go to the parts house for R152a. Thats right the general public can buy refrigerant and legally release it straight into the atmosphere. I bought 3 pack packages at Sams Club for something like $8.00 and they were 12 or 16oz cans. Charge capacity is about 60-65% of R134a.

TTOP350

iTrader: (8)

Learning..

Fast355

iTrader: (2)

Several of us R-152a converts are happy with how it performs compared to R134a in the same systems.

http://forum.gmtruckcentral.com/show...t-check-it-ouT!!

1982Z28Modified

OK Fast... I will try R152a... only because the GM study claimed 10%. I expect real world results of about 5%. Remember the GM study took place in a lab, not real world conditions.


Quality of parts is huge. Check out Four Seasons chinese crap. Low quality.


I see the Dusting Air comes with a "Bitter" to discourage huffers. Do you know of a brand that doesn't contain a "Bitter". And what psi should my cycling switch be set at?

Fast355

iTrader: (2)

Have not found it without the bitterant. As for pressure, split the difference between R12 and R134a and try it. Pressure temperature curve is similar to R12 but even R12 systems leave a little on the table.

formula1LE

iTrader: (3)

Well, I definitely will be trying it out in my Shortbox project soon then. If nothing else curiosity has bitten me! Lol. I don't think the AC could ever be "too cold" here in the muggy midwest....then again, if I get my interior too cold I don't wanna end up cracking my perfect truck dashpad due to frost!!!! lol

1982Z28Modified

Well after some trial and error, I finally got my a/c charged with R152. New compressor, new accumulator, new orifice (VOV). Washed out the evap and condenser with denatured alcohol. Changed out the Schrader valve in the liquid line with a new 134/152 compatible valve. All said and done the system took less than 30 ounces. Original fill was 48. Now to see how it runs the next few says.

Ozz1967

iTrader: (4)

This was a fun read! Can't wait to see how it turns out.

TTOP350

iTrader: (8)

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