Quote:
Originally Posted by RandallNeighbour
|
Resurrecting this old thread since I'm getting neck-deep into my Boxster's AC system.
My AC stopped working probably 3 years ago, so I just stopped using it. Now that I'm getting things restored & back to stock -- I've checked through enough fuses & relays to be an expert at the electrical side of the AC system, and I bought a gauge set to check pressures while I hotwire the compressor. The only electrical issue is that the pressure switch is open, but I'm trying to focus first on the compressor and just making sure there's enough refrigerant in there.
With the pressure sensor open, depriving the compressor of its voltage, to check the pressures I've hotwired the compressor relay with 12V from the nearby spoiler relay. When I look at the pressure gauges, hi & lo are both 30 psi. I expected the high side to pop up in pressure, at least a little. This led me to fear my compressor is shot, or the expansion valve is wide open. (?) But I can't help but wonder if it's been so long since the AC was used, I have a "bootstrap" problem with unusually low refrigerant...
I already tried buying a can of "AC Pro" and brought the system up to 30psi from about 20. So it was definitely low before. I'm afraid to go any higher in pressure since instructions say not to, but...
What's the static AC pressure supposed to be after not driving for a while? Mine is at 30psi now, first thing in the morning, or car on, or compressor running, both high & low sides of the expansion valve. I'm wondering if the pressure is sooo low, the compressor isn't "grabbing" any of it, the high side isn't going high, and the low side isn't getting sucked down to where it ought to be, given the (possibly) low amount of refrigerant. I'm wondering if I should just "give it hell" and put a bunch of R134a into the system, the compressor will finally start gulping enough refrigerant to work, high will go high, low will possibly get sucked *down* to ~20psi in pressure once the compressor starts operating properly, and then I can continue topping off to ~30 psi.
The fact that the pressure sensor is open (indicating a fault) would seem to back this up, although I have no documentation about what pressures the sensor/switch is looking for. However I'm afraid if I go too high on low-side pressure, in defiance of instructions (even though they all assume the compressor is actually functioning) that I'll damage something with over-pressure.
Has anyone had experience with this particular corner-case?
Thanks,
-Kevin.