Hi all...
After the weather started warming up here I began noticing that my '03 Forester's AC wasn't blowing cold (barely below ambient) and an annoying hissing sound was coming from behind the dash. Suspecting a low refrigerant charge and not wanting the compressor to eat itself I disconnected it until I was able to borrow a manifold gauge set and check things out. The last time I worked on a car AC system was back when R12 was still legal and a recharge meant checking the site-glass for bubbles while you put in a can or two of refrigerant. Anyway, I figured I'd try my hand at an R134a system and hopefully not break anything. When I hooked up the gauges I found low pressure on both sides of the system (in fact the low pressure side would pull a vacuum when the compressor ran). Figuring a low refrigerant charge was the issue, I put in a can of refrigerant/lubricant/sealant. After this the vents were blowing air in the temperature range I thought they should. When I checked with the gauges the pressure was better, but I'm still not sure it's right. The low side would read upper 20's (psi) and the high pressure side would read about 175 psi with the engine running, but the compressor clutch disengaged. When the compressor would kick on, the low side would drop down to about 10-15 psi and the high side would get up to about 220 psi at which point the compressor would cycle and the pressures would rise/drop to their initial values. So I have the following questions for anyone with more experience in this area than myself:
1) Is what I'm seeing with the pressures normal? The shop manual I have didn't say anything about the pressures being either steady or varying - just provided a range (18-28 psi low side, 213-242 psi high side). Do the pressure swings on the gauges indicate a problem somowhere? At this point I'm thinking the system is touch low of refrigerant but am reluctant to tap another can just to top up the system. Could leaving the charge a little low cause problems?2) When I first removed the screw cap from the high pressure side of the system, there was a small gas release and the inside of the fitting was wet with oil. Is this normal or do I have a bad schraeder valve? The paranoid side of me is wondering if the last time I had it in the shop for a non A/C matter if someone there vented my refrigerant charge as an attempt to drum up future business. If a little leakage of refrigerant and oil through the high side valve is normal, then I can straighten my foil hat and get on with my life. :-)
3) Is refrigerant leakage from Subaru air conditioning systems like this normal? Should I just plan to periodically recharge it or do I need to have it checked out by a pro?Any information would be appreciated.
Advance
- Snuffy -