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tripletauto, ASE Certified Technician
Category: Car
Satisfied Customers: 502
Experience:  ase certifed master tech gm certifed 20 years experience
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Isuzu Trooper: Hey I have a 1991 Isuzu Trooper V6 GM engine.

Customer Question

Hey I have a 1991 Isuzu Trooper V6 GM engine. After a lot of troubleshooting with AC system I found the compressor was bad and leaking. I just replaced it with a re-manufactured AC Delco one. It bolted up fine and I filled it with 60ml of PAG-50. Then charged the system with R134a and it was running fine. I noticed a little strain on the system when AC was on, but that's normal. Then about 10 minutes later it started to get noisy. wondering if I didn't add enough PAG.
Submitted: 5 years ago.
Category: Car
Expert:  tripletauto replied 5 years ago.

did you drain oil out of old compressor and measure?

you should do that and add same amount if less than 2oz add 2 oz oil.

Customer: replied 5 years ago.
The old compressor leaked so there was barely any oil in it. Is there an actual specification chart or something? (the install sheet had same info you just gave which is why I added the 60ml oil) I'm just afraid I did something wrong, because it sounded fine initially but started to sound worse.
Expert:  tripletauto replied 5 years ago.
it is possible needs more oil since it was leaking. adding another ounce will not hurt system. if you have an oil or dye injector this can be done without opening system. Install gauges and see how pressures look if building pressure this may be why noise and we need to address that.
Customer: replied 5 years ago.
I don't have an oil or dye injector :/

I'll explain what I did in detail

1. removed old compressor

2. installed new one (AC Delco 15-21736 remanufactured)

-removed intake cover

-poured in 60ml of PAG-100

-installed new seals

-bolted up to engine

3. splice new electrical connector on as stock one wasn't compatible

4. Charged system with R134a from Autozone to about 35PSI

5. Turned on, all seemed good, AC was cold, compressor clutch spinning

6. Drove around and noticed strain on engine, not crazy strain though

7. started to hear a bit of noise/squeal

8. turned off engine
Expert:  tripletauto replied 5 years ago.
low oil will usually cause a rattle type noise in compressor. What you describe could be high side pressure building too high.which we need to have gauges on to be able to see. possible causes of this are trash clogging condenser or blockage in system. did you check belt to see if loose?