1986_IROC-Z

So, I want to get my car's AC working again, and I'd like to do it myself if possible.

The factory Harrison compressor is fubar'd and wasn't connected with a belt when I bought the car last year. There doesn't appear to be any pressure in the system (verified by pushing in the pin on the low side?).

Which sounds like a better plan?

Option 1 (DIY + shop):
-Replace compressor with a reman R4 from NAPA. Fill with correct volume of PAG oil.
-Replace condenser
-Replace accumulator/dryer
-Replace orifice tube
-Replace any other o-rings in the lines.
-reassemble system, but leave belt off
-drive to local dealer or shop, have them flush and recharge $$$$$

Option 2 (DIY only):
-Replace compressor with a reman R4 from NAPA. Fill with correct volume of PAG oil.
-Replace condenser
-Replace accumulator/dryer
-Replace orifice tube
-Replace any other o-rings in the lines.
-Flush hard lines and hoses (take off car, run solvent through them)
-reassemble system
-buy a set of manifold gauges and vacuum pump, pull vacuum
-if vacuum holds, refill with correct quantity of R134a, ensure high and low pressures are within correct ranges when running.

I'm not sure the condenser replacement is absolutely necessary. May be smarter to leave the factory condenser on there and pull vacuum first. If there is no leak there, leave it. A new compressor is about the price of a new condenser, and the compressor is a lot easier to replace (I think).

Thoughts, advice? This is my first rodeo with working on AC...

Drew

iTrader: (58)

I'll have to keep an eye on this thread...

Last summer I overhauled the A/C in my 87 Iroc, and 91 Formula. Both cars I reused the compressors, condensers, hoses, etc just with a good flush and new seals, new dryers, and orifice tubes. Vacuumed, recharged, and both worked well initially. Before the end of the summer, the 87 already stopped kicking on. I'd suspect I have a leak, but I haven't gotten too excited about tracking it down. The 91 still blows ice cubes.

I personally despise 134A. It's personal opinion, but I'd blackmarket a kidney for R12 before I put R134A in a system designed for R12.

I've heard nothing good about remanned R4 compressors. Maybe NEW ones are OK, IDK. Personally I've been collecting used R4's, and hope I have enough on hand to keep my cars cold.

I don't like making appointments, or trusting the minions at service places to work on my cars. So personally, I'd buy the gauges and vacuum pump and DIY.

Do plenty of searching and reading, there has been a lot discussed here on this topic.

sofakingdom

iTrader: (1)

My opinion is different from Drew's on that matter.

I've written up a how-to on AC systems countless times. Search for my userID and the phrase "orifice tube", and take your pick.

I prefer remanned compressors to "new". Most "new" ones are Far East manufactured knockoff pieces of crap. Not even sure you can still buy a new Delco / Harrison / GM R4 anymore, or that you'd even want to do that. At least with a reman you get an actual GM compressor.

A better choice, if you're worried about its reliability, might be to look at the Sanden or Denso or other similar modern one, which are not hard to retrofit into our cars. Search on Sanden, I don't recall the details but I think somebody posted up part #s, sources, photos, or other such info, that will make it much easier to see what has to be done. Personally I couldn't give a rip about "originality" in this matter; "original" isn't worth a crap to me if it means retaining some old Stone Age thing that was inferior in its day (the R4 is a GREAT example of the American auto industry's "malaise" years, kinda like the 305) and hasn't got any better in all the years since. Something best left forgotten in the dustbin of history. I have no desire to drive around a rolling museum that's horribly unreliable just for the sake of it being the same as it was when it was new.

Even though I have a license to buy R-12, I won't do that anymore... WAY too expensive, and like Drew points out, it usually all leaks out anyway. I always replace the compressor, accumulator, and rubber lines; flush the evap and cond COMPLETELY with solvent; and refill with 134A. Again, a brief search as described above will net you some pretty complete instructions.

Drew

iTrader: (58)

I've read a bit about adapting the better aftermarket compressors, and I like the idea, but usually the packaging bugs me. They always look tacked on and rigged. Oh well... I stuck with the used compressors I had because they were free, so nothing to lose.

To be clear I used an alternative to R12, not R134a. If I were more confident in the integrity of the system, R12 would have been my preference. I went with other because of the experimental nature of my project. Again, I had nothing to lose by trying the alternate.

I'm no expert on the subject to be sure, just participating in the topic to learn. My approach was 50% effective, in a limited sample. I hope to try again on the Camaro this spring. By all means feel free to disagree and correct me if I'm mistaken. lol

1986_IROC-Z

Thanks for the replies so far. Sofa- I'll check out your writeups.

I was thinking of a re-man compressor because as sofakindgdom said, at least it's a real R4 (not that they were great, but it's still a GM part).

On originality, well, that's kind of the whole point of me owning this Camaro. The goal here is to "restore" the AC system to working condition. It doesn't need to be the coldest AC, but the system needs to work and be in good condition.

I'm thinking R134a because it's cheap. Of course R12 would work better, but I don't want $$$$$$ of R12 leaking out on my first AC job if it doesn't go well. This also isn't a daily driver.

NoEmissions84TA

iTrader: (1)

You can get R12 on eB**.

1986_IROC-Z

Yeah. It's more about price than availability. R12 seems to be about 3x-4x the price of R134a. If I botch the first recharge, I won't feel too bad about losing about $30 worth of R134a.

Camaro510

So with weather channel saying we are going to have "the hottest summer in a decade" here in Cali, I need to restore/replace my ac unit too. Subscribed for more info!

1986_IROC-Z

Sofakingdom - a few more questions, if you have a moment.

First, I read through your threads, and I picked up a couple of tips-
a. 100wt PAG oil
b. Flush with non-residue solvent (acetone is my choice)
c. Orifice tube from a '96 Crown Vic
d. Verify good working condition of cooling system including radiator cap, cooling fan(s), radiator, and making sure if I reuse the existing condenser, to clean it up for good airflow.

Some questions:

1. I see automatically-adjusting orifice tubes, two different models, one for less than 105 degrees ambient, one for over 105 ambient. Would getting one of these be any better than a Ford/Red orifice tube from a '96 Crown Vic?

2. Do reman or new compressors (or dryers? I'm not sure where the switches are located) usually come with high/low pressure cutoff switches? If yes, will it be obvious if they are for R12 or other refrigerant pressure?

3. You mention to empty 3 cans of R134a (presumably 36oz) into the system. What are the correct high and low pressures, or how are those determined based on ambient temp? I'm assuming the procedure if pressures are too high to...ahem...recover some refrigerant from the system?

I'm getting ready to order parts...thinking I'm going to go with the local Napa outfit so if I need to return parts I can do it easily. Rockauto seems to have better prices, but I've never dealt with them before and they're not local.

4. Any guiding on who does a better reman compressor - Murray, Four Seasons, other?

Thanks in advance!! I'll keep this thread posted for the others who have subscribed. I'm off next week and plan on tackling the job then.

1986_IROC-Z

Parts bought (and the rest ordered!) This project is becoming a reality.

The compressor, accumulator, and R134a "conversion" kit (o-rings, fittings, etc) are on order. Picked up the Ford orifice tube, all new belts, R134a refrigerant, manifold gauges and vacuum pump today.

The compressor is coming 5-7 day ground shipping. So, I'll probably post some updates late next week or the following week on progress.

Camaro510

About how ,uch is this costing you and what reference videos/articles/threads are you using? Please and thank you. I found some interesting ones, but I don't understand any of them yet lol

1986_IROC-Z

So, here's the parts list I am working from based off of Sofakingdom's threads. Search this forum to find previous threads by him/her

Total today at the NAPA parts counter was $490.

Compressor (Reman R4 w/ 5.5" pulley correct for an '86 Iroc) - $148
Accumulator/Dryer - compatible with R12 or R134 refrigerant
Orifice Tube (from a '96 Crown Victoria to help with <105 degree cooling temps)
Barrier hoses - I didn't order these, mine were aftermarket and appeared to been good shape already.
O-ring kit - $35 for all o-rings, adapter fittings for the old R12 stuff, and a random bottle of ester oil which is not needed....
3x12oz cans R134a - whatever the going rate is
Pag oil (100wt) -- I was only able to find 150wt at Napa. I'll look again, but this was a cheap/negligible expense.
AC/ps/water pump belt - cheap expense. BUT, you will need to know the 8th digit of your VIN code
Alt-water pump belt - cheap expense
air pump - belt - cheap expense.

Manifold gauge set - including "vacuum pump" which connects to a regular compressor - $147 from parts store.
Vacuum pump - included in above.
Acetone for flushing - cheap....$8/can?

Saxondale

iTrader: (2)

Watching this thread. My car will need pretty much the same this year. Looking for another lazy man's go-to thread. I'm the lazy man. There may be other threads, but so far this one describes my car exactly.

NoEmissions84TA

iTrader: (1)

You can get a gallon at Home Depot or Lowes for maybe $12.

sofakingdom

iTrader: (1)

AZ and equivalents have PAG oil in an assortment of weights. It'll be something like 40/50, 70/80/100, 150. You want the middle one for our systems; not super critical what the exact number is, just, not the super thin or the super thick.

Acetone is an excellent flush choice.

Instead of "$35 for all O-rings", get one of those GIANT $10 assortments that has like a million of em in every size EVAH. Much better deal. Over time you'll be glad you have em.

Change the hoses. PERIOD. No sense in taking a chance on something THAT CHEEEEEEEEP ruining your finished product. Use the SOOOOOOPER HEAVY DOOOTY A/C hose clamps, NOT the "heater hose" ones hanging on the card in the aisle. Use 2 at each joint to guarantee as good a seal as a high-pressure hydraulic crimp like the factory. NAPA has those, consumer type places are tougher to find em.

Murray and 4 Seasons are both good old reliable names for that sort of thing. Not to say that they're 100%, as nothing ever is, but they're at least a known quantity. Which is not to say that lesser names aren't a good option too. I think, if you go to a reputable store (NAPA, CarQuest, and those other national chains), those guys serve professional shops whose livelihood depends on getting it right, and they don't carry stuff - at least, not once you get out of the "bargain basement" price level - that doesn't work right the first time nearly every time for the pros. Like anything else, you tend to get, AT MOST, what you pay for; just avoid the mistake of getting the cheeeeeeeepest, and then your odds will be heavily in your favor.

You can probably "rent" a vacuum pump some kind of way. Not sure myself, I have my own, but an A/C supply or maybe a welding supply place would be a possible source. I've also heard of people making one out of a refrigerator compressor, which seems perfectly plausible, but I've never done it so I can't say how likely it is to actually WORK.

You'll probably want 4 cans of 134. THIMK: R-134A only VERY RARELY accumulates in the atmosphere (of this pitiful planet, anyway) in a sufficient concentration to ADD TO whatever you put in there... more likely, whatever you put in, is gonna leeeek OUT OF your system. Makes sense to start out with SLIGHTLY (emphasis on "slightly") too much. That way, over time, as the inevitable occurs, your system will sort of improve toward "perfect" for awhile before deteriorating, instead of cratering starting the very instant you take off the charging hose. There is NO SUCH THING as "perfect" in this area: there is ALWAYS error and compromise and imperfection and leaks and other manifestations of physical reality experience, you need to be smart enough to make the error work FOR you, instead of AGAINST you.

mikeceli

iTrader: (2)

I too have had no luck w/ R12 to R134A conversions. R12 cost about 2 to 2 1/2 times as much as R134A, not bad as long as it doesn't leak out.

Id consider Ester oil, since it's compatible w/ 12 and 134.

Fast355

iTrader: (2)

Just a thought here...Even my factory R134a systems have been getting R152a in them. Cools much more quickly and gets much colder. My 1997 Express van has seen vent temps of 38°F on a 105°F day. Even at idle with a 25% underdrive crank pulley it will get down to about 45°F.

instro84

last summer i bought an 89 trans am that needed ac work, i replaced the condenser, had the lines rebuild replaced recover dryer, then took it to a shop and had them vacuum it down and check for leakes then fill with oil and freon and it works really good even out in so cal desert where temp get well above 100 in the summer. got all the components except condenser from rock auto.

1986_IROC-Z

Update: Still waiting on parts.

Third-gens are pretty rare in this area, so Napa stocks literally nothing for them. The reman compressor is coming from New York and I opted for ground shipping; tomorrow will be 8 days so I'll call them tomorrow to see if stuff is in.

I completed the flush. To do this, I ordered a flush can from Amazon to hook up to the air line on my compressor. Filled the canister with acetone and "blew multiple loads" through the condenser, evap, and lines. The evap box had some junk in it, used my compressor to clean out the evaporator fins, vacuum to clean out the evaporator box. Well worth taking apart. Then, resealed with dense foam weatherstripping to the firewall.

Overall the system was very clean. The oil was clear and the orifice tube had almost nothing in it, which leads me to believe one of two things: a) all the blown-out compressor shavings were in the condenser, or b) the compressor suffered a seal failure and blew out all the oil and refrigerant--consistent with the oily spray pattern on the hood liner above the compressor.

I'm ready to finish this project ...once parts are in I need to see about renting a vacuum pump. Or, I need to get down to Harbor Freight and buy one.


Any questions people want answered? I'll try to document the process of reassembly, vacuum, and charging as best I can.

NoEmissions84TA

iTrader: (1)

If I remember correctly, the system must be kept under vacuum for many hours.
Most let it vacuum all night long. If you are going to use the HF vacuum pump
that uses your air compressor to generate vacuum, then your compressor will be
running for many hours. Rent the proper vacuum pump.

1986_IROC-Z

You are correct; my Bostitch 5-gallon compressor does not have enough wallop to run an air-driven vacuum pump.

I will be renting or buying an electric vacuum pump that can keep the system as close to 30mmHg as possible.

NoEmissions84TA

iTrader: (1)

1986_IROC-Z

It's taken me a while to get after this project, lots of stuff going on right now. But, I've been able to steal a few afternoons for myself, and just finished up everything except for the charge tonight.

Everything is flushed, cleaned, and re-assembled. I installed the R134a retrofit fittings for both the high and low ports. Installed the new dryer, installed the new compressor. Everything has the new green o-rings where there once were black o-rings, and I coated all the threads and o-rings in Nylog, which was a tip given to me on this site.

The compressor came pre-oiled with 3oz PAG 150. The total system capacity is 8oz, so I put 2.5 in the accumulator and then sucked another 2.5 into the high side by bumping the vacuum. There's no need to suck it in the high side like I did; I simply had forgotten to add the other 2.5oz in the lines when re-assembling.

I closed everything up and vacuumed it down. First for 10 minutes, then turned everything off and let it set for 15 minutes or so to see if it would lose vacuum quickly. Nope, appears sealed.

Then I vacuumed it for 45 minutes or so, mostly to test out the pump while I was cleaning up the garage. It's pulling darn near 30mmHg, and it didn't get too hot (Harbor Freight special, 2.5cfm vacuum for $79). I closed all the valves and will see how it does overnight.

If the vacuum holds, then tomorrow I'll charge the system and see if I did everything right!

NoEmissions84TA

iTrader: (1)

I hope it all works out for you. Sounds good so far.

Fast355

iTrader: (2)

Something to consider for everyone reading this. I use the Ford .062 orifice tube. Should be Red in color. I also like to use the LT1/LS1 F-car fans. Between the two you can get the a/c temps down in the mid to low 40s at idle with R134a. If you switch the orifice only without the more powerful fans you will run at a higher head pressure and will not cool as well. The factory cycling switch also needs to be adjusted with R134a to allow the pressure to drop a little lower before the compressor cycles at highway speeds. It will probably never cycle at idle, but running 40+ MPH it will. If you run the fan on high/recirculate and bring the RPM up to 2,500 rpm I like the accumulator just to start picking up a slight layer of frost before the compressor cycles.

1986_IROC-Z

To my disappointment, the system lost about 20mmHg overnight. However, it was late when I shut everything down last night, and noticed the blue hose line connection wasn't tight at the AC fitting, and the red one wasn't all the way tight at the manifold gauge set. It's kind of annoying that the gauge set didn't come screwed together all the way from the factory, but, bad on me for not checking.

So I'm doing another vacuum test to rule out those bad gauge connections.


I am also using a Ford red orifice tube. However, I am using the original/ single fan and serpentine style condenser. I know that's not optimal. A newer condenser (parallel flow?) and dual, high-speed fans would help the situation.

I did adjust the low pressure switch (1/4 turn down from where it was)

1986_IROC-Z

I'm thinking I have a leak somewhere. The system drops 1-2mmHg/hr with the vacuum off and the gauge valves closed.

I did a leak test on the gauges, and they held just less than 30mmHg overnight, so the gauges and all the hose connections seem to be good.

I've snugged a few connections and re-did a few others to check o-rings, vacuumed it down again for 45 min+ and it didn't hold, either.

Next steps: pressurize the system with shop air (~90psi) since I don't have access to Nitrogen. Maybe pressurizing the system will confirm a leak (or confirm that the leak is only persistent under vacuum).

If that still shows a leak, then I'm going the old-school route of partially charging the system with refrigerant and dye, and checking for leaks with a black light.

1986_IROC-Z

Pressurizing the system with compressed air @ 90psi seemed to hold for an hour--no loss compared to vacuum.

So I went ahead and charged the system. I vacuumed for 90 minutes prior to charging.

The target goal was 38.4 oz R134a (48oz system capacity R12 from factory x .8)

I emptied 4 cans (48oz total in the system), however there was some good loss, so I'm guessing I'm right around 40oz or maybe a as little as 34oz.

Observed pressures after the charge were - the compressor would cut off at a low of ~25 psi and it would cut out on the high side ~250psi. Low side pressure with the compressor off was 40-ish?

Is that acceptable? Ambient temp during the charge was about 58 degrees and 90% humidity.

Here's where it gets stupid, and I'm totally perplexed about what I did wrong:

I can only get vent temps (Max AC, blower on full speed, at freeway speeds) is around 54 degrees. Whaaaaaaaaaaaaat the F. I was expecting somewhere in the low 40's.

The timing of cycling and the compressor sound is like that of a normal AC compressor cycling.

The large line/ low pressure is cool to the touch, both it and the accumulator are sweating while the AC is on.

Help?!

DynoDave43

iTrader: (11)

I'll let one of the a/c gurus tell you for sure, but when we tested vent temps at our dealership, it was with the blower on low, and all of the other vents shut. I don't recall us using the recirculate (Max) setting.

Think of it this way. There's only so much "cold" to be introduced into the air (or more correctly, only so much capacity to remove heat). Your temps will never, at any time, in any system, be as low with a high blower speed (greater quantity of air) as with the blower on low (lower quantity of air).

sofakingdom

iTrader: (1)

Humidity also has a MASSIVE effect.

As in, it takes about 5 times as much heat transfer to remove the water in 95% RH air to get it down to say 50°, as it does to cool the air from 95° to 50°.

Which is why AC systems work SO MUCH BETTER in the desert than in New Orleans.

Frankly I'd live with it for awhile, and see if it's sufficiently adequate enough, before getting all wound up about the number you see on a gauge. That gauge won't tell you whether you're "comfortable".

You can get AHELLUVALOT more heat-moving capacity by working on the cooling system (radiator fan etc.) than trying to finesse the AC system itself. I'd suggest starting there if in the end it doesn't .... DO IT ... for you. Maaybe a Taurus fan or something. Maybe even, just cleaning out the leaves and dead cicadas and rodents and whatnot between the condenser and the rad, if you haven't already.

1986_IROC-Z

Thanks man, you've been a big help.

Can you comment on the pressures I should be at? And when the pressure should be read?

When the compressor is pumping, blower on high, Max AC setting, it's at about 30psi on the low side. The high side continues to climb to 250, and at that point the compressor shuts off until it cuts in again at ~25 psi.

Static pressure on the system was taken in the garage, approx 60 degrees F. It matched the mark for 60F on the pressure gauge.

I ran the AC today with the car outside, and recorded the weather conditions. 53 degrees outside, 80% humidity. Not ideal for testing AC...

I saw center vent temps anywhere from 42-48 Degrees at the coolest with the compressor on. I recorded one of the side vent temps briefly at about 40 degrees, however, shortly after, I never saw that temp again and vent temps were in the high 40's low 50's. Is it possible I froze the evaporator or one of the lines and it just wouldn't cool?

1986_IROC-Z

Bump / TTT

If anyone can help, I'm trying to figure out what pressures I should be running high side/low side and when to check them.

My AC just isn't very cold - even as it's gotten into the mid 70's here the AC is still pretty warm inside the car.

I can't tell if the system is over-charged, under-charged, or if a single cooling fan and serpentine style condenser just sucks that bad with a R134 conversion.

Biledriver

See if your cooling fan can hold a strip of paper against the front of the condenser over most of its surface. That way you know it's cooling the whole thing well. The better it's cooled the more gas you can get in with the same pressures. If that is ok you may have to much oil built up. That can keep it from holding enough refrigerant and the condenser and evaporator from exchanging heat properly.

Vader

My WAG is that the orifice tube may not be passing enough liquid. Making 250 PSI on the high side at 53° ambient seems just too high, considering the 30 PSI evaporator pressure.

Vader

Perhaps a little review would reinforce some of the ideas above.

https://www.thirdgen.org/forums/tech...questions.html

What was true 15 years ago hasn't changed.

Fast355

iTrader: (2)

Sounds undercharged as well as lacks airlow to me. The orifice size he is running passes enough refrigerant to get my front a/c unit in the 1997 Express down to 38°F on a 105°F day. Using high fan speed and Recirculate.

Fast355

iTrader: (2)

I will also add I went from R134a to R152a in the same Express van and went from mid 40s at idle to 38°F at idle with the compressor cycling about once a minute.

One other thing to consider is your heater core dumping heat into the evaporator case. It is super easy and cheap to add a ball valve into the hose coming off the intake manifold between the engine and heater core. Close the valve and you block off all the heat going into the case. Even just the hot heater core sitting in the a/c/heater box hurts the cooling capacity of the system.

1986_IROC-Z

The cooling fan operates properly and is not damaged. That's to say, it works like the engineers intended it to, back in 1986...

If the system is undercharged, how do I know how much refrigerant to add?

On the initial charge, I took the system capacity (48oz R12) and used .8 as the multiplier to get 38.4oz R134 needed. It comes in 12oz cans, so I added 3 full cans and a good portion of the 4th can since I was bleeding the fill hose between can swaps. I was trying to keep track of the total R134 weight using a food scale.

So, not sure where to go from here. If the system is low, how do i know if it's topped up? If the system is overcharged, how do I know how much refrigerant to recover?

Thanks in advance..