1999 Legacy OB, 2.5, 135,000 miles
My a/c is only blowing kind of cool air when I'm on the highway cruising between 55-70 mph. The moment my rpms decrease (like exiting the freeway) to where I'm just city driving/idle, the a/c is warm. The compressor is engaging at idle, but it clicks like mad. It sounds like I'm riding a bike with a baseball card in the spokes. Here it is:
Suspecting I might be low on freon and, because I just bought the car, I decided to go ahead and do complete recharge so I know it's got the right amount of freon. I pulled a vacuum and put in about 20-22 oz of R-134a. Didn't make a difference.
On the manifold gauge set, the low side was reading a constant 65psi when I filled it and it never fluctuated unless I revved the engine and then it would go down to ~50. The high side always seemed to be between 200-300.
What could be the problem? It seems like the high/low side gauges would fluctuate on my other vehicles while the a/c was running. In this case, they are constant. Is that normal? My relays all seem fine. Is my compressor dying?