AaronSorenson

2 weeks ago I finally fixed the AC in my wife's 1992 Civic LX. It worked for 4 days. It had been evac and filled by a shop. The day it broke it was driven from northern utah 100 degrees during the day, to las vegas (115degrees) where it broke. What happened is the relief valve on the back of the compressor blew. It was filled to the proper pressure. Why would this have blown? Is the relief valve reusable (just replace the O-ring)? Any help would be great.

ezone

The service info I have indicates the high pressure relief valve should be replaced once it has vented, as it may open at too low pressure next time.


Did the valve go bad?
Or did it open to vent excessive high side pressure?
Need to know which so you can look for the root cause.

Was the system a bit overcharged? ("Filled to the proper pressure" means nothing. Systems should be charged by the weight of the freon.)
Does the condenser fan work correctly?
Is it pulling air the correct direction?
Is the condenser airflow blocked?
Damaged?
Little fins in the condenser all bent over from 24 years of road debris hitting it?

Is this a R-12 system?
Was it using R-12 or has it been converted to R-134a?
Or was it running some other type of refrigerant?

AaronSorenson

I watched the mechanic fill it, it was filled with 20oz with R134a. The system calls for 21-23oz. So it shouldn't have been high pressure. But it leaked all the freon out of it. Should the system take the same amount of R134a as R12? Thanks again

AaronSorenson

The condenser looks pretty good, a few fins bent but not many, it's pulling the correct direction. It all worked awesome last summer. I did an engine swap over the winter.

ezone

ALL the freon, or just some of it?
If it ALL leaked out from the valve and the system does not hold pressure, I'd probably replace the valve and seal (as it would seem broken as opposed to protecting the system from excessive pressure) but right now I don't know what the exact failure with the valve was.

If it has been converted, then it should take less R134 than it did R12.

If a conversion was done correctly, it should have a new corrected capacity sticker telling how much R134 it should hold.
If it still has the original R12 sticker....I have a note saying to subtract 1-2/3 oz from the R12 capacity spec. so what went in sounds pretty close.

AaronSorenson

Thanks again for your help. I replaced the valve with another off of a spare compressor I had laying around. I'm still not sure why it blew, but it all seems to be working now. Thanks