legacycentral bbs

My 94's a/c is bugging me. Most of the time everything works fine. Nice & Cold, good airflow at the right places. Heater works great. Sometimes, the compressor does not kick on in any of the modes it is supposed to.(DEF, DEF/Heat, Max A/C, A/C) I think it is my switch that is maybe going bad. After reading a lot of threads I am unsure on how to bypass the switch to confirm my suspicions.

Pat

Pat,

Is there any correlation to outside temperature when the compressor doesn't work? I'd be curious to know the AC pressures. The compressor may not be turning on because of low pressure in the system. I think the 94 is 134a so you should be able to get one of those refrigerant cans with a gauge on it and check the pressure when the AC is off. Then we can see if it's below the AC pressure switch's cut off limit.

Josh,

Outside temp does not seem to matter when it happens. It has happened in the cool morning when I hit the DEF switch & when it's warmer out in the afternoon. I do have one of those interdynamics r134 cans. While I do not remember the actual PSI it was in the green zone. I will check it again & get back to you.

Pat

Edit: The pressure was 35-40PSI with the compressor off & 25PSI with the compressor on. Blowing very cold.

Yeah, that should be high enough. I'll see if I can find the pressure switch info so you can test.

Thanks. I really appreciate the help. I think the problem is starting to get worse. Yesterday on the way to work, the A/C was fine then the compressor shut off & would not come on for a few minutes. Then as I was fiddling with the buttons it stared up again.

Pat

Here's the info from the FSM's:

http://main.experiencetherave.com/subar ... h_Diag.pdf
http://main.experiencetherave.com/subar ... h_Diag.pdf

I think the information is the same/similar, but presented a little differently. There is no additional information in the 93 & 94 FSM supplements so the 92 is what should be applicable.

I wouldn't rule out bad solder joints in the HVAC control unit, especially if the trinary pressure switch checks out ok.

Thanks. I will look at it when I get off work.

is the 93 134a?? tell me yes, id love to recharge the system in my one car that ive had with ac for a decade or so haha

ride_child wrote:is the 93 134a?? tell me yes, id love to recharge the system in my one car that ive had with ac for a decade or so haha

There should be a sticker on the radiator mount saying what the a/c system is charged with. Not sure when Subaru made the change but my 94 has r134a & my 92 that I used to own was still r12.

Pat

I'm pretty sure 94 was the first year with 134a, but yes check the sticker.

This is frustrating. I spent a bit on my day off trying to figure this problem out. When I want it to not work it will work every time. Kind of hard to diagnose a problem if it is not doing it. Yesterday after work, close to 90F, the a/c would not engage. I get about a mile from work & all of a sudden it comes on & woks fine the rest of the way home. I am about ready to just start throwing money at the problem.

That sucks. Sorry to hear about this Pat.

As I mentioned above, I wouldn't rule out bad solder joints in the HVAC control unit.

Well, just as a follow up, I replaced the HVAC control switch with another one with 176k instead or 256k that mine has. So far all works as it should. Only time will tell. Last week my A/C worked great for 2 days. On the 3rd day it would not engage. After about 15 minutes of messing with the buttons, it came on. Here's hoping.

Pat

Pat,

Are you talking about the HVAC control unit in the dash?

Yep.

Ok, hopefully the new one continues to work for you.