Scotty562

I just got my car a few months back and i recently turned on the ac to find it reved the engine up a little but kept doing it over and over again, with 5 - 10 seconds inbetween each rev. Also the air comming out of the vents never realy gets cold.

After doing research i believe that i need to recharge the system. However you need a licence to buy r-12 coolent...

I was searching around and i found r-12 to r-134 conversion kits.

Should i take it to a shop and have them recharge the ac, or would i have to take it to the shop to have the r-12 drained anyway to have r-134 put in it anyway.

As far as i know auto stores sell conversion kits, but im not to sure what all is involved with the process. Insite would be greatly appreciated.

dankhound

The cheap $20 conversion kits come with new fittings. If the proper charge is added to your existing system, it should cool fine with the conversion.

If the R-12 is still available you could go with that option too.

I would ask the shop the cost of each option and go with the cheaper of the two.

Scotty562

what should i expect to pay? i'd like to know what i should expect to pay for obvious reasons .

I'm guessing they will have to find where the leak was, replace wahtever it was, then add new r-12 or the conversion, whichever is cheaper.

FAST RS

When i had my car converted to R-134 it was 75.00 and i had them suck all the R-12 out of my car and put it in my moms car. R-12 was going for 60.00 a lb then.

Scotty562

and that was with all labor charges?

FAST RS

Ya that was with labor and the conversion kit.

Scotty562

Is there a way i could find a leak in the ac system on my own?

dankhound

Finding a leak is something that is better left to the pros. Its not the type of leak you will usually be able to see.

Rage13

use 409 to check for leaks, best stuff i've found so far. first things i'd check are the hoses and the service ports, the little schrader valves often leak..
and i wouldn't convert to 134a, it don't work as well. you can use some freon called "Hotshot" its like a cheap version of r12 but works just as well

TA5LiterHO

134a works just fine as long as you use the correct amount. My car cools exactly the same now as it did with R12. All I changed was my burned up compressor and charged it up. Blows at or under 50 degrees out of the center vents.

Where does one get this Hotshot stuff out of curiosity? How does it cost compared to the 134a?

Scotty562

you didnt change any lubricants or tubes? just the compressor?

Just out of curiousity, will any compressor work from any car? As long as the size is right.

TA5LiterHO

Oh no, you have to lubricate the system or it will burn up. I used a 134a kit. The older kits had a can of oil and a couple cans of refrigerant.

Now the oil lubricant is mixed in with the refrigerant in some kits. The recharge kits.

You have to use the compressor that goes with your car. Some cars are serpentine belt driven and some are vbelt driven like my car. The vbelt compressors cost less. I paid about $90 for mine.

I did not replace any orfice tubes or anything if that's what you are asking. The car is an 84, but 2 years ago when I replaced the compressor the car only had about 50,000 miles on it so all I did was the compressor.

Scotty562

How did you flush the old r-12 out?

TA5LiterHO

The best way to get the old stuff out would be to evacuate the system so that no moisture gets in there or the system could start freezing up.

Now that I think about it, my system was full of R-12. I could have just put r12 back in, but I figured if I needed a little more I wouldn't have any extra so I went ahead with the 134a.

thirdgen88

If you do a retrofit, put a new accumulator and orifice tube in and have somebody bring it to a vacuum. My other advise would be to use the ford (hope thats not censored. ) blue orifice tube.

I did the retrofit on my GTA (new accumulator, new standard orifice tube, new o-rings, fresh charge) and it cools very well (about 45 degrees vent temps on an 80* day with max a/c at idle). However, my brothers 91 bird cools about 5* cooler with the only procedural change between our two retrofits being he used the blue orifice tube..

91TPI5.7

Hotshot is a drop in for R12, 134a, and 502. Mainly used in refrigeration, it has also been approved for use in mobile air conditioning. No oil change is needed, same pressures as r-12, a lil higher on the head. Only drawback is it is a blended refrigerant. What this means is if a leak occurs, then the refrigerant begins to fractionize. This is when one or more of the components leaks away, which chemically alters the original refrigerant. So if there is a large size leak, you cant just top it off. You have to evacuate and add a whole new charge. On the plus side, one mall can (12 0z??) same size as the 134a cans, is like 12 bux. More than 134a, but you dont have to do a total retrofit. Just evacuate the system and add the HS. Which outways the other. I got r-12 in my camaro, and HS in the blazer, cant enjoy it in the blazer, gotta bad compressor. But i have done at least 4 other cars with this and at idle temps have ranged between 38-44* on a 85+ day.

thirdgen88

One thing I forgot to mention is to remember to adjust the clutch cycling switch after you do the R134a retrofit (the stock switch cycles the compressor off at around 25-26psi low side, with R134a, that needs to be around 19-20psi)..

TA5LiterHO

How do you adjust the clutch cycling switch? When I ran my AC for the first time this summer yesterday the Compressor never did cycle off while I was testing it.

DENN_SHAH

iTrader: (1)

the pressure may not have gotten low enough to cycle off. but to adjust it, pull the connector off the low pressure switch on the accummulator & if there is a screw between the terminals on the switch then it is adjustable, i think turning the screw counter-clock wise will lower the cycle pressure.

red90bird

keep in mind if you use somthing besides -12 or -134 you have effctively contaminated your a/c system. granted it may work but if it dosen't work you will have to find a shop that will take out the blended stuff. recovery equipment is expensive and most shops will not want to contaminate thier supply with a blended refirgerant. just somthing to keep in mind. ohh I'm sure you already know this but the longer you pull a vacum on your a/c system the better results you will get because the inside of your a/c system will be clean.

TA5LiterHO

Thanks for the info. I am gonna look into that today.

DENN_SHAH

iTrader: (1)

you don't want the compressor to cycle off too soon, if it does then it won't cool as good as it can. ideally you want the accumulator to frost up some & then it cycles off. if you have it set too low the evaporator will freeze up & you won't have good air flow through it. the way i set my cycle temp is to drive it around & get the inside of the car cooled off & pull it in the shop, with the windows all up, doors closed, a/c set to max & the blower on it's lowest setting run it at a fast idle & watch the accumulator. i think the low side pressure is about 25 pounds when it cycles off.

Scotty562

I got ahold of a vacuum, are there any steps prior to just attaching it?

I also heard something about using compressed air to clean out the system. What is involved with that.

Basicaly, howdo i get the r-12 (if any is even in there) out.

red90bird

well first of all, do not use compressed air; its just not a good idea. second of all to get the r-12 out hook up your vacum pump and just let it go, the longer you let it draw a vacum in the system the better off you will be. personally I would let it go at least an hour.

TA5LiterHO

I understand that the compressor needs to stay on long enough to cool the air. Thank you for bringing that point up though.

86LG4T56

I recently got my hands on my Dad's 86 Firebird, with a dead a/c, and he told me he was pretty sure it had already been converted to R134. He was the only owner, so I assumed he would know. But when I went to Wally-World, and bought a bottle of refridgerant, the bottle's nozzle is larger than the little bicycle-looking nozzle on my accumulator. The stuff sprays everywhere! Am I putting it in at the wrong place, or is there some way I can tell if it's been converted?

thirdgen88

You did get a can tap and hose, right??

It should have a quick-connect fitting. If it doesn't have an adapter on it, its probably still R12...

86LG4T56

Yeah, the can comes with a hose and quick-connector. It cost like $11 instead of $6 for the cans that require a seperate hose. It's just that the quick-connector is much bigger than my nozzle. My accumulator nozzle is like dime sized, while the can's connector is nickel sized. The accumulator nozzle is just like a tire nozzle, threaded and everything.

jconrad

Here's what they should look like if it has been converted.
*EDIT*
Those new quick connectors just screw right on the old schrader valves.

Formulater

which is high pressure and which is the low pressure?

thirdgen88

The low side fitting is on the accumulator..

jconrad

Umm, just a thought. Freon does not evaporate, and it is not used up like say, oil is. So for it to not be working, there is either a leak in the system (usually the o-rings from sitting), or one of the components are not working correctly. The orifice tube gets clogged, the accumulator also is like a filter, so that can get clogged up too. The fins on the condensor pick up all kinds of road debri (usually bugs and leaves). Your sensors can go bad, making it not work, as well as the seals inside of the compressor. But most older compressors are alot more reliable then today's newer ones.
I would pull a vacuum on it, and then hold it, to see if there is an evident leak. Another way to tell is to carefully inspect all the lines, usually a leaking line will have oil/grime built up right around where it is leaking. If all this fails, then charge it, but make sure you add some of the dye in there, to see if it does leak out over time. If you look at my low-side fitting, you can see where the dye sprayed when I was removing the connector. Oops. But so far, no other dye trails anywhere.
The molecules of R134a are actually smaller than R12, so if you have a slight leak with R12, it might turn into a much larger leak with R134a.
Just my .02

RebelTillDeath3

To the original post, the compressor is short cycling if it is coming on/off/on/off/on/off, which means the level of R-12 is too low. Go take it to a professional A/C tech. (no matter how easy it may seem, there is way too much that could go wrong) and have the evac the system, do a dye test for leaks, and recharge it.

Catchen22

you know it's just my personal opinion but I would stick with the R-12. I just recharged my system after detecting a leak and fixing it. I live in arizona and the summers are extremly hot. But after recharging my system, and leaving it on for about 20 minutes I have to turn it on the lowest setting cause it gets too cold, but thats not a bad thing.

86LG4T56

I've always wondered if the a/c causes more horsepower loss when it's set at its coldest setting compared to say halfway up to warm?

black89ws6

Where you put the temperature selector has very little, if any effect. Air moving through the vent system first moves through the evaporator core, then through the heater core (if the lever is moved toward the hot side), so your ac system has to cool the air the same no matter where you put the temp lever.

Where you put the fan switch will effect how much power your ac system is using. The higher the blower, the more air moving through the evaporator core. This transfers more heat into the evap. core. This is more heat the ac has to pump to the condenser...therefore more work, which in turn means more energy consumption.

Turning the blower to a lower setting reduces power consumption several ways.

1) when the compressor is running, it is pumping less heat, therefore consuming less power
2) the compressor will cycle off for longer periods of time with the blower at a lower setting.
3) blower fan uses less electrical power.

If you're wanting to reduce power loss to the ac, just leave it in max, lever at full cold, and use only as much fan as it takes to be comfortable.

86LG4T56

Alright, last dumb question:

What's the difference between Max and Norm anyway?

black89ws6

Norm draws air from in front of the firewall (under the windshield wipers...outside air, basically). Max recirculates the in-cab air. If you look in the far corner of the passenger footwell, there is a door to the fan that only opens in max mode.

Max will easily get you another 10 degrees cooler air.

marineengineer

Question? When doing the changeover from R12 to R134a, has anybody replaced the condensor to a late model condensor? If you have, what if any fitment problems have you experienced?

The reason why I ask is due to R134a have a lower specific heat capacity that R12. That means R134a will not absorbe as much heat for system volume as R12.

In shipboard refrigeration, we have replaced the condensor, ie to a condensor with more cooling tubes to achieve the required heat removal which effects the high side head pressure.

I wonder if would make a difference in our cars???? It should as this would allow more heat rejection/system capacity and lower head pressure



I am aware of changing the orfice tube to the "Blue Ford tube" helps out a lot. Just interested if any of you a/c Mecks. thought about this??????

black89ws6

R134a has a higher specific heat than R12. About 30% more. Condenser efficiency is so much more important for that reason. R134a has to give off about 30% more heat (per unit mass) than R12 in order to condense.

R134a is about 10% less dense than R12. When you put that together with it's latent heat difference, you have a refrigerant with about 20% more latent heat per volume. That's where the ford blue tube comes into the equation. It's cross-sectional area is about 15% smaller than the standard gm tube. It reduces the refrigerant flow rate somewhat, which reduces condenser heat load to a level closer to an original R12 system.

I think I read a few posts a long time ago where some guys put 4th gen condensers in, but I think they had to fabricate their own mounting brackets and condenser lines. If it's going to take that much effort to make it fit, I'd try an aftermarket parallel flow condenser. They're supposed to be even better than OEM 134 condensers. Check this thread for some info https://www.thirdgen.org/techbb2/sho...hreadid=245989

My system is still functioning on it's original R12, so I haven't had to worry about it yet, but when the time comes, I'm going to try to fit one of these parallel flow units in mine.

bulletboy29

Someone told me that if your car was used on dirt roads frequently, that the coils would probably need to be cleaned. Is this true? If so, how would I do this? My air works fine, but it isn't quite as cold as I think it should be. This car was used on dirt roads daily before I got it. Any help would be appreciated!

black89ws6

Yes! This is most definitely true.

If it's just dirty, though, it's easy to fix. Hose out your condenser and radiator with a garden hose and a spray nozzle. Don't forget to do the radiator, too! Air that goes through the condenser also has to go through the radiator. Hose them out in the reverse direction of airflow first (this will help to dislodge larger objects), and rmove the top radiator mounting so you can pull the radiator back a few inches. Clean out the area between the condenser and radiator. This is a popular places to collect leaves, twigs, and other assorted garbage that blocks airflow. Hose out this area once you've got it clean. Once that's done, hose out the condenser from the front side (under the bumper). Take a good look at it while you're down there. If you've got a lot of bent fins (which is quite common), that will reduce airflow as well. To fix that, you will need a "fin comb" to straighten them out.

good luck

bulletboy29

Thanks black89ws6! I'll check that out today. It has got to be dirty if it is anything like the rest of the car was when I got it!

GTA350VORTEC

I have an 89 GTA, but am having problems with my daily driver, a 97 Jeep Grand Cherokee. It is a stock 134a system. I think I over charged it with oil. How can I remove the oil from the system? The compressor is cycling, but the air stays warm. Please help its getting hotter here in NYC. Thanks in advance for any help.

Rage13

if your compressor is cycling your low on freon and have a leak somewhere

GTA350VORTEC

Ive always had a small leak, but it never effected how cool the air was, plus I cant get the system to take in anymore freon...the charging hose guage is all the way in the red when I attach it to the low side.

GTA350VORTEC

Ive always had a small leak, but it never effected how cool the air was, plus I cant get the system to take in anymore freon...the charging hose guage is all the way in the red when I attach it to the low side.

black89ws6

Was the ac running when you got that reading with the gauge?

GTA350VORTEC

The AC was running when I got that reading, should it have been off?

black89ws6

No, it should be running.

Does the gauge give a pressure reading? That would be helpful to know. I can't be certain without that information, but it sounds like you're overcharged, or your compressor is weak and/or bad