[jonKranked]

What sort of problems / symptoms are you experiencing?

If you're going to replace those two items, you might as well replace the dryer and the expansion valve too.

i didn't really think much of it, it really only blows cold air when the car is in motion (and the engine is revved up), and the air gets warmer when i'm stopped; like say at a red light or in traffic. it also apparently doesn't sound like its supposed to.

 

[Katz]

i didn't really think much of it, it really only blows cold air when the car is in motion (and the engine is revved up), and the air gets warmer when i'm stopped; like say at a red light or in traffic. it also apparently doesn't sound like its supposed to.

Best case, it's just low on compressor oil and R134. In which case, all you need is getting the system vacuumed & refilled. Or the condenser has lots of crap built up on it. Spraying it with a pressure washer from the radiator side will usually take care of that.

If you see ice forming on the expansion valve, the valve is starting to clog up.

Not so awesome case, the compressor is on its last leg. Unless the compressor has already started to spit its guts into the system, you probably won't have to replace the condenser and the evaporator.

I'm just a shade tree mechanic with basic understanding so that's about all I can offer. Good luck to you.

 

[jonKranked]

Best case, it's just low on compressor oil and R134. In which case, all you need is getting the system vacuumed & refilled. Or the condenser has lots of crap built up on it. Spraying it with a pressure washer from the radiator side will usually take care of that.

If you see ice forming on the expansion valve, the valve is starting to clog up.

Not so awesome case, the compressor is on its last leg. Unless the compressor has already started to spit its guts into the system, you probably won't have to replace the condenser and the evaporator.

I'm just a shade tree mechanic with basic understanding so that's about all I can offer. Good luck to you.

thanks for the info. i took a look with the hood open last night, didn't see any ice, but then again wasn't specifically looking for it, or that closely.

 

[Katz]

Hey @jonKranked, one more possible suspect if your Subaru has electric cooling fan(s). Those fan(s) get triggered not only by engine coolant temp, but also threshold pressure on AC system. I forgot about it since I still drive pre-historic vehicles with mechanical fans

A properly designed AC system maintains the high-side pressure below a certain level (300-ish psi) by itself at cruising speed, but at lower speed, it needs some extra air forced through the condenser. When that fails, the compressor clutch disengages until the system pressure dips below the safe level, causing an issue similar to yours.

If you're not hearing the fan kicking on when you're sitting at a traffic light with AC on, try hooking the fan directly to a 12V battery. If the fan turns, check wiring (relay, fuse, etc) and AC pressure sensor. The sensor should be somewhere on the line connecting the compressor and the condenser, and usually easy replace (Shrader valve underneath)