AC question

[rayeve]

My wife has a 2005 Legacy, non-turbo. I was trying to max out her cooling today (it's 104 outside here in Dallas at the moment).

 

A chart I have shows that at 100, which it is at the moment, the low side psi should be pulling about 150 to 155. I can only get hers down to 140 no matter what I do. And dash outlet temp is about 42.

 

NOW, odd thing is her CABIN temp gauge is (presumably) broken because it's showing 85 degrees when I first sit down in the car after overnight. It's way more than that in reality. I SUPPOSE it's just a coincidence that 140 psi should be what I'd get if her cabin temp gauge was right and it really was just 85 in the cabin and outside. I.e., there's no way the cabin temp gauge can directly limit the psi the compressor is running, is this correct?

 

I can think of two more things going on as possibilities:

 

1) there is air in the system. As I understand it air won't compress much compared to AC gas. And the car has had a very slow leak for two years. But since the pressure in the system has never gone down a lot below normal, it seems the direction of leakage would only be towards the outside of the AC system?

 

2) maybe the compressor really is starting to go from old age. (The car has about 133,000 on it).

 

Any thoughts among you AC guys about what's the most likely problem here?

 

Thanks in advance.

[iNVAR]

There is no cabin temperature gauge. That is the ambient outside temperature reading. And either way, it won't have anything to do with your AC functioning.

 

As far as maximizing the AC, my car's AC runs great in the summer when the car is at cruising speed, even when it's 100+ out. HOWEVER, when your car is sitting in traffic or idle in the sun, it's going to suck. Also 42 degrees at the vent/outlet seems fine, especially if you took that temperature while the car was idle or in traffic.