I have 2 quick questions for anyone that works in automotive AC.

1. Do you have to add AC compressor PAG oil every time you evacuate, vacuum and recharge, or only when the compressor is replaced? AKA does all of the oil come out as well when you evacuate the system? Same thing for purge? (unintended purge. Had a high pressure line go out).

2. Do you have to compensate the refrigerant for the compressor oil you add?

For example. If the system takes 22 oz of refrigerant, and 4 oz of compressor oil, do I add 18 oz of refrigerant?

I want to make sure I don't overcharge or undercharge the system.

Thanks guys

 

The answer to these questions vary because we dont know if you're recharging, had swap out bad parts, or redid the entire system.

 

Replaced compressor, drier, condenser, evap core, seals, and expansion valve. tested for leaks and good. Charged it up with an industrial shop R134a system. Everything worked well for 30 days. Then the high pressure line went out a month after unexpectedly, and I lost all of the refrigerant. Replaced both lines and about to recharge.

I am wondering if I have to re-add the PAG oil. If so, do I have to compensate the amount of R134a?

 

Did you check the service manual? I'm pretty sure your questions are answered there.

You definitely need to add some oil. Did the replacement compressor have oil in it?

If you want professional help, you'll need to pay for it. On a forum, you get what you get. But it's free.

 

You are suppose to add oil before testing. I went by the helms manual, it tells you how much goes into each component.