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Previa A/C Leak

thecritic on Fri August 28, 2009 7:12 PM User is offline

Year: 1992
Make: Toyota
Model: Previa
Engine Size: 2.4
Refrigerant Type: R-134A
Ambient Temp: 75F
Pressure Low: 35
Pressure High: 175
Country of Origin: United States

My father has a '92 Toyota Previa. It was a garage queen up until about 2003. Currently, it has 87,000 miles on it.

Back in 2005, the original R-12 charge leaked out. The leak was at the service port fitting. So, we had the service port replaced and the system recharged with R-12.

About six months later, I saw a pool of oil leaking out of the rear evaporator drain hose. Of course, the system was empty again. Not knowing any better, I took it to a neighborhood mechanic. This mechanic decided to replace the rear evaporator core with a new one from the dealer, even thought this wasn't the problem. After completing the repair, he recharged it with R-12.

Since the leak was not solved by replacing the evaporator core, the R-12 charge leaked out in a matter of weeks. This time, the same guy flushed out the system, replaced the receiver/drier, installed new Ester oil, installed new service valves and charged with R-134A.

Of course, converting the system to R-134A didn't do much for resolving the leak. Frustrated, I decided to remove the access panel to the rear A/C evaporator. Once I removed the access panel, I noticed that the rear A/C expansion valve was wet with oil. The access panel also had a lot of oil on it. In addition, when I have the rear a/c running, I hear a hissing-like sound that sounds like oil is leaking out of the system. I am guessing that the expansion valve is leaking oil, and therefore, freon is leaking out along with the oil?

To confirm my diagnosis, I took it to Pep Boys for a diagnostic and their ASE technicians agreed with what I said. They told me that because the evaporator valve is leaking oil, I needed to replace the valve and install new o-rings for the connections. They also installed a dye into the system and were not able to find any additional leaks.

Therefore, is the rear A/C expansion valve the source of my problems? If a valve is leaking oil, is it true that refrigerant is leaking out with the oil? Lastly, the freon sniffer wouldn't pick-up anything from the valve, even though it is already leaking oil.

Thanks in advance!

Chick on Fri August 28, 2009 9:52 PM User is offlineView users profile

The oil comes out with the refrigerant, if the valve was "wet" I would guess it's leaking, an O ring or the valve itself.. Hope this helps.

Email: Chick


Freedoms just another word for nothing left to lose

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