cwigg66

Anyone know what the green capped plug is on the A/C dryer? It plugs into a small manifold on the inlet side if the dryer, right before the low pressure switch. The wires and electrical gismo appear to be all one piece. The reason I ask is that my A/C compressor clutch (brand new) doesn't come on despite recharging and checking all pressures following a new compressor installation. I've had intermittent trouble with the old compressor not kicking in for a few minutes and then randomnly starting, despite the A/C button being depressed the entire time. Always assumed it was a pressure issue, but the air was always blowing cold when it actually turned on, so I didn't give it too much thought. Now, the compressor clutch can only be engaged by running direct 12V to the clutch wire.

FYI, I DO NOT get 12V at either of the wires to the low pressure switch, which leads me to believe the relay is the culprit, or the A/C switch itself, or the little green thing by the dryer. I do hear a clicking from under the driver's side dash when I hit the A/C button, but the compressor does not engage.

Any help would be greatly appreciated.

Thanks

Chris W.

xsboost90

if its on the dryer it should be a high pressure switch- if the compressor is coming on and going off it may be short of gas. There is a glass bubble on top of the dryer, when the car/compressor is running there should be no bubbles in that sight glass- charge till it is clear and stop.

cwigg66

Charged it yesterday to 40PSI low side and about 190 PSI high side. Keep in mind that it is only about 60F here, so I don't know what the pressures should be for the ambient temp outside.

I do have LOTS of bubbles in the site glass. However, I don't have 12V on either side of the low pressure switch, so even if the charge was right, it still wouldn't engage the clutch. Can the high pressure switch go bad? If so, how do you replace it? I've never seen on for sale, and it is hardwired into the harness, so you'd have to cut it out and splice a new one back in.

944Ross

The circuit diagram calls that a "refrigerant temp switch", it may actually be using temp to detect a high pressure condition. At any rate, its function appears to be limited to controlling fans, not the compressor. I'd look upstream of your LP switch for a wiring problem or bad switch.

Yarf

AC Relay G17 ?

cwigg66

Checked the A/C relay (popped the cover and monkeyed with it), and it seems to be working consistently now. Maybe the contactor in the relay was out of adjustment. In any case, it's an impressive relay. Appears to be all copper.

Thanks for the help all.

Chris W.