Automotive Air Conditioning Information Forum (Archives)

kwandobe on Tue May 31, 2011 8:41 PM

Year: 1991
Make: Pontiac
Model: Trans Sport SE
Engine Size: 3.1L
Refrigerant Type: R134a
Ambient Temp: 85F
Pressure Low: 60
Pressure High: n/a
Country of Origin: United States

Hello all! This is my first time to this forum and I hope I'm not too complicated.

I have a 91 Trans Sport which I just retrofitted with new r134a ports! Before I filled my low side I wasn't getting any reading of volts to the clutch coil. So I filled the low side to 60psi and viola, 13.55volts! My RPMs rise when I select A/C, otherwise there is no other changes, the coolant fan doesn't spin with A/C selected. I tested my coil and I show anywhere from 4.1 to 4.2 ohms at the coil, however the clutch plate doesn't even move a hair(and the compressor doesn't spin) with the A/C turned on.

Currently my blower motor doesn't work on high, I had a problem before winter where my blower motor didn't work at all, so I changed the coolant fan relay which did the trick and fixed my controls. 3/4's of the way through winter my blower quit working on high. So hopefully we can run tests without my blower working on high?

Does anyone have any troubleshooting I can try or comments to my post?

Thank you all in advance! =)

mk378 on Tue May 31, 2011 9:22 PM

You need to do a proper retrofit. Merely filling a R-12 system with R-134a will ruin the compressor because the oil is not compatible. The kit in a box with the little can of "conversion oil" is useless. Professionals call it a "death kit" for a reason.

As for why the compressor doesn't engage, first possible reason is the clutch coil is getting power but not ground,On some systems it is grounded through a high pressure cutoff switch. The other reason would be the coil has power but the plate won't pull in because the air gap is too wide. But again you should be glad that the compressor did not run.

kwandobe on Wed June 01, 2011 1:50 PM

I am planning to have the system dried, just want audible and visual verification that my clutch and compressor seem operational. But what you're saying is not to use the quest kit I bought because it doesn't have PAG or ester oil in the cans? If that's the case I had might as well toss it =(

The reason I started filling my system is because I can't find the low side switch, I followed the low side line from the evaporator to the compressor, no switch. I followed the high side line and found the high side switch though. I attempted to jumper the high side switch before filling the system, no voltage at the coil, so I filled the low side a bit.

The high side switch terminal has some calcium build up, but it's really small and looks like it will be hard to clean. Sand paper and dielectric grease?

Thanks =)

mk378 on Wed June 01, 2011 8:47 PM

If it's a 3 wire device on the high side that's a sensor, not a switch, and you can't jump it. Variable displacement compressor systems such as yours do not cycle during operation. Thus there is typically no switch on the low side.

kwandobe on Thu June 02, 2011 4:05 AM

It must be a switch then as it's only a two wire harness, and should I use the quest kit after I have the system dried, or not a good idea? lol

Thank you again for your help =)