Fiero V6 keeps blowing A/C compressors while sitting (Page 2/2)
steve308 JUL 25, 02:35 PM
On your comment " I'm wondering if maybe I'm putting in too much oil?" Compressors are shipped with oil in it. Did you drain and measure it or did you just add oil to the system? If you didn't drain and measure before adding that would be the issue.
CharginPegasus88 JUL 25, 03:32 PM

quote
Originally posted by Dennis LaGrua:

From my A/C work on cars the cause of a failed compressor can be:
1. A defective reman unit. Very likely
2. Debris in the system/ clogged condenser. Common
3. A severe overcharge of the system. Possible
4. Failing to put in a new orifice tube and a new accumulator. A mistake
Be sure to check high and low side line pressures after the install by referring to the temp vs pressure R-134A chart. I would always recommend using a new A/C compressor.
When recharging use Ester oil then put A/C setting on max cool and also occasionally rev engine while recharging. I additonally use a thermometer at the vent outlets. if you measure around 40*F your there.




1. The compressor has been replaced twice now. First was a reman, so probably a dud. The second (see pictures posted above) was a new Four Seasons aftermarket compressor. Both failed the same way.
2. When I replaced the original compressor, debris was present in the orifice tube filter. I fully disassembled the ac system. Both the evaporator and condenser were removed from the vehicle and flushed out. All lines were flushed individually as well. No debris has been found in the screen since the flush.
3. When charging the system, I use 2 cans of r134a with no leak sealer or other additives. This is 24oz of refrigerant which is about 75% of the original R12 charge, so it shouldn't be overcharged.
4. I replace the orifice tube and drier every time I recharge the system. I have been using a standard orifice tube. Maybe a variable orifice tube would work better.

I have been using 8 oz of PAG oil in the system. I know ester oil was the original spec and that ester and PAG don't mix, but seeing as I fully cleared the system, I figured there would be no issues with oil mixing and hurting the system further.

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1988 Fiero Formula 2.8 intercooled turbo

CharginPegasus88 JUL 25, 03:39 PM

quote
Originally posted by steve308:

On your comment " I'm wondering if maybe I'm putting in too much oil?" Compressors are shipped with oil in it. Did you drain and measure it or did you just add oil to the system? If you didn't drain and measure before adding that would be the issue.



So the reman came with an unknown quantity of shipping oil in it. I drained it, then put 4 oz in the compressor, 4 oz in the drier.

The new compressor came with 3 oz of oil in it. I drained 1.5 oz from the old compressor and 1.5 oz from the drier. So I installed the compressor with the prepacked oil.

It seems like a lot of oil gets caught in the condenser with these cars. When I flushed the system, it seems like a lot of oil was trapped there.

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1988 Fiero Formula 2.8 intercooled turbo

Dennis LaGrua JUL 26, 04:12 AM

quote
Originally posted by CharginPegasus88:


So the reman came with an unknown quantity of shipping oil in it. I drained it, then put 4 oz in the compressor, 4 oz in the drier.

The new compressor came with 3 oz of oil in it. I drained 1.5 oz from the old compressor and 1.5 oz from the drier. So I installed the compressor with the prepacked oil.

It seems like a lot of oil gets caught in the condenser with these cars. When I flushed the system, it seems like a lot of oil was trapped there.



Flush remaining in the system can hurt a compressor by dampening the lubrication factor. Also PAG oil is recommended for new systems only not retrofits and that is why I use only Ester 150 oil. An amount of old 525 mineral oil remaining may be hampering the effectiveness of the PAG oil. PAG and mineral oil do not mix. Ester and mineral oil do. Did you fully evacuate the system to 29in/hg before charging? .Also check your R-134a cans and make make sure that they do not contain a oil R-134a mix. When you attach the charging hoses before charging do you turn the refrigerent on and bleed the hoses of air before charging. Those are the only items that I can think of


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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 07-26-2021).]

Craig71188 JUL 26, 07:27 AM
1) Fiero uses a GM HR6 compressor that has a crappy design (pressed case halves). If you have had 2 leaking mid compressor check for misalignment on the mounts. Any twisting forces as you do your final tightening of the mounts can twist the cases and cause leaks. Also, prying on the case halves to tighten belts can cause leaks.
2) I show a 40oz. charge for '88's. 32 oz would be 80%, then temperature test and add to full charge. 24 oz is grossly undercharged.
3) Evacuating the system should be to 29 inches of vacuum for NO LESS than 30 minutes
4) Check voltage to compressor clutch. With lights/blower/etc on you should have NO LESS than 12V at the clutch. Lower voltage will cause the clutch to slip and overheat the front seal


Temperature Test:
Car at idle, max AC, doors open, let run for 5 min to equalize
Check temperature at evaporator. Evaporator inlet (after the orifice tube) and outlet temperatures should be equal (+/- 5 degrees). DO NOT base this on duct temp as duct temperatures will actually rise slightly as you reach full charge. An undercharged orifice tube system WILL NOT move oil and you will destroy the compressor relatively quickly.
Check inlet/outlet at condenser - you should typically have about a 30 degree drop (give or take 10 degrees)
Check ambient air temp to duct - your temp drop should be close to the condenser temp drop.

Based on the fact both compressors cooled and then didn't, I would be most inclined to look harder at #1 & #4 above.

BTW...I work for 4Seasons and did AC training for technicians for many years. Most compressors (new and reman) get killed by junk left in the system, or by installation issues caused by misinformation. If you could only see the crap that comes out of "defective" compressors when we get them back.....
skywurz JUL 26, 08:35 PM
Bunch of older posts recommend 25oz. I did 32 in mine and had issues with the high pressure kicking off the system under load and it freezing over. I changed to 25oz and things run much better.