1997 Legacy GT AC got progressively worse and then stopped altogether, would cool when engine was revved but not at idle, and now not at all. Got a can of refrigerant with a gauge on it, hooked it up to the low side, and to my surprise, showed pressure up in the red zone. I really thought it was low refrigerant, especially after seeing bubbling at the valve after I took the cap off.

 

Any ideas on the likely cause of this? Sounds like some sort of blockage but I don't know where to look. Will probably take it to shop but would like to know what to expect so I don't get taken for a ride.

 

Thanks in advance.

From messing with mine, it sounds like you may either have some air or the preasure is to high. Hopefully Josh will chime in. He seems to be the guru on the subject.

 

 

Do a search on ac and see if you can find anything

 

Jim

Did you try adding some refrigerent?

 

You may want to take it to a shop. It'd be nice to know what the high side pressure is.

 

Most shops have an ac diagnosis service for like 20 bucks or something.

Did you try adding some refrigerent?

 

You may want to take it to a shop. It'd be nice to know what the high side pressure is.

 

Most shops have an ac diagnosis service for like 20 bucks or something.

 

I didn't add refrigerant because the cheap pressure gauge that came with the can showed it as already too high, in the red. I guess I could hook the gauge up to the high side and get a reading.

I didn't add refrigerant because the cheap pressure gauge that came with the can showed it as already too high, in the red. I guess I could hook the gauge up to the high side and get a reading.

 

Is the sub-fan running? If that does not run the pressure gets too high at idle and the high pressure opens and stops the compressor.

Is the sub-fan running? If that does not run the pressure gets too high at idle and the high pressure opens and stops the compressor.

 

I'll check that out, thanks. It was not cooling before at idle, only when the revs were up, so that sounds like a possibility.

 

(I couldn't check the high side pressure because the fitting that comes with the can doesn't fit on it.)

Was the pressure read with compressor running?

1997 Legacy GT AC got progressively worse and then stopped altogether, would cool when engine was revved but not at idle, and now not at all. Got a can of refrigerant with a gauge on it, hooked it up to the low side, and to my surprise, showed pressure up in the red zone. I really thought it was low refrigerant, especially after seeing bubbling at the valve after I took the cap off.

 

Any ideas on the likely cause of this? Sounds like some sort of blockage but I don't know where to look. Will probably take it to shop but would like to know what to expect so I don't get taken for a ride.

 

Thanks in advance.

 

Most likely a restricted expansion valve. It's located at the evaporator (inside the vehicle under the dash). Expansion valves can become plugged with tiny bits of metal as a compressor slowly wears out. I've seen people try to clean the inlet screen on expansion valves in an effort to re-use the part; that depends on your budget and skill level with A/C systems. Probably best to simply replace it and be done with it.