Hello again, I hope all you Volvo folks are doing well.

My A/C compressor is cycling on and off for a few seconds each time.

When I bought the 91 with the R-134 conversion two years ago the A/C
did not work. The Compressor Clutch would not kick on.

Then last year I flicked the switch on and she worked slightly cool,
so I didn't use the system.

Last month I flicked the switch and got sligthly cool air, but didn't use
the A/C much.

I thought the system needed R-134, so I attempted to add some this evening.
The compressor clutch cycles on and off for about 3-5 second and does not
take in any of the R-134.

Any advice would be appreciated in this 90+ weather in New Mexico.

Thanks in advance,
Joseph Segura

All Fixed.... I will be a cool cat today.

But, how do I know if the pressostat is adjusted correctly?
I unscrewed the screw a little at a time until I got the
compressor to stay on, but now that it has the R-132 should
I re-adjust it back? Or how does one test the agjustment?

Thanks to all,

Joseph

The compressor should cycle once in a while to prevent the system from freezing up. The following write-up in the 700/900 FAQ may help:

http://www.brickboard.com/FAQ/700-900/HeatingAirConditioning.htm#ACCompressorClutchCycling

The cycling on/off is generally indicative of a low charge, but why it won't accept any more refrigerant is odd. Are you using a charge kit with a guage?

You might try disconnecting the plug at the pressure sensor and jumping the contacts in the plug. Then see if the compressor will run steady and give you cold air at vents. You don't want to run the compressor this way TOO long just incase it is actually low on charge, but you should know within about 10-15 seconds if you are going to get cold air especially if you run the RPMs up to about 1500. If it seems to give you nice cold air at that point, you may have a sensor switch that is out of adjustment. I've heard that some of them are easily adjustable but I have never done that myself.

Another possibility is that it's OVERcharged, as R134A supposedly has a narrower pressure range that it performs well compared to R12. But I don't know if the pressure switch opens in an overpressure situation. I'm guessing there is just some reason the Refrigerant won't flow from the can into the system, like some sort of obstruction or some little gizmo missing from the valve or your charging hose. Did you try running the RPMs up a little while charging in order to drop the pressure on the low side of the system?

Thanks for responding.
The kit does have a guage and we had just charged up another automobile
so it seems to be working.

I just jumped the pressure sensor and the compressor runs steady and gives
cold air at the vents when jumped. Then when I replug the pressure sensor
it runs on and off again quickly.

So, at this point it seems as if I need to adjust the sensor or replace it?

Thanks for your help.
Joseph

When you had the refill hose connected, did you see the desired pressure indicated on the guage, or are you not able to get enough into the system to reach the desired reading?

I adjusted the pressostat sensor and now the compressor stays on.

With the refill hose connected, when the compressor kicks on the reading stays at about 25psi. When the compressor kicks off or I unplug the sensor the reading goes very high into the red.

The R-132 is not going into the system, the can stays full. The R-132 can and the receiver/drier do not get cold as did on
another automobile that we fill with R-132 yesterday.

The air coming out of the A/C is so so cool, not cold.

I unscrewed the adjustment screw only a small bit and this helps keep the compressor on.

When I unattach the R-132 can from the receiver/drier I don't get a puff of pressure like I expected when I pull it off the receiver/drier.

Please help its getting hot in here.
Joseph