Hi. My Subaru Forester 2002 air conditioner doesn’t cool continuously. It’s nice and cold most of the time but stops cooling after about 45 min of driving. I can usually get it to cool again by turning it off for a few minutes and back on. I already changed the cabin filter which made it colder when it does work but it still has the problem. My otherwise trustworthy mechanic wants $150 to drain/fill the system for trouble-shooting. This seems like a good approach if it were leaking but I don’t think it is. Please advise.
What you’re describing sounds like a faulty expansion valve to the evaporator.
My car A/C was doing something similar. I took it to the shop.
The mechanic found the system was low on refrigerant (leak) and had to recharge the system, as well as put some dye in there to find the leak later.
Why are you so confident the system isn’t leaking? Being a 2002, a leak wouldn’t surprise me at all.