AC weirdness

My wife's 2005 Legacy non-turbo has been having the AC go from working to not working on the same 30 mile each way commute for about a month. I.e., it'll work awhile, and then quit, and then work again sometimes. For about a week it hasn't worked at all.

This a.m. I checked the low side pressure (at about 61 degree F.) and found it to be about 70psi -- which must surely be too high. (Unfortunately, I couldn't check the high side because the needle on the gauge is missing!). Does this behavior sound like a compressor? Or are there other likely reasons for this weird behavior?

Did you check the low side pressure with the AC on or off?

 

That is acceptable pressure for that temperature with the AC off. If the AC was on, then yeah, there is a problem.

Yes, I had the AC and fan both on high. However, in retrospect, I don't know that I ever heard the ac clutch turn off or on. If it's the clutch, it might explain why wife reported that if worked well when on, and not at all when if would episodically quit working. I've never heard of a compressor itself working sometimes and not others?