86 951 Driver

Preface the history of my A/C System. Rebuilt Compressor and R134a conversion done last summer at a Porsche specialty shop (high quality shop).

Driving the Porsche yesterday I had the A/C on with the recycle button pressed. It was working great on the highway and seemed to kick off the compressor. The air didn't seem to be quite as cold. On the way home it was not blowing any cold air and the compressor was not on. The A/C button was pressed in and appeared to be lit up, but the compressor for sure wasn't running. I haven't check pressures, but I don't think freon would do a mass exit from the system in a few hours time. I suspect my A/C button is not making the proper connection to turn on the compressor. Is there a way to test that switch or somehow by pass the switch by connecting a few pins on the wiring harness? Possible relay?

I checked the clark's garage but there isn't a testing sequence for the switch.

mytrplseven

I wouldn't rule out a catastrophic exit of the coolant. Any refrigeration system will do that. My house system just puked itself one day after getting recharged. I'd go back to the shop before I'd start diving into the wiring. They can quickly check to see if the charge is ok. They can do a leak check as well.

odonnell

Isn't the AC compressor clutch on its own relay? I would check that and the fuses related to the HVAC system. Should be easy to check with a multimeter and other basic tools.

86 951 Driver

I'm trying to get some R12-R134a hoses for my gauges.

http://www.ebay.com/itm/R12-to-R134a...5c9f7a&vxp=mtr

86 951 Driver

How would I be able to tell if the switch is sending power to the compressor?

odonnell

The switch in the dash? I would take it out and test with a multimeter. Set it to test resistance. If the switch is on and the resistance is infinite (9999.999 Ohm or whatever), the switch is bad. If it's good (which I suspect) I would test the leads to the clutch. Disconnect from the compressor and check for a voltage across them. I don't have an AC system in my car, nor do I have my Haynes manual in front of me right now so I can't tell you exactly which wires you should be checking. But wiring diagrams for the clutch can't be that hard to find.

86 951 Driver

I swapped out my HVAC controls for another set. No change. I looked at the "Heating" fuse as well as the blower motor fuse. Both were good.

I don't know if the relay is okay or not. Can you make a jumper similar to the DME relay?

I need to get conversion fittings for my car, what are the correct ones for our car?

86 951 Driver

Found the issue today. One of the contacts on the low pressure switch broke off. Can I replace the switch without drawing down the system?

william_b_noble

no, when you take the switch out, the refrigerant will escape - maybe not all of it if you work fast. If it is already low, then you can change it and not panic over pulling a vacuum, If I remember right, when not running the pressure is about 20 psi, so you might be able to just change it, if you don't mind screwing the new switch into a hole that is spitting oil and refrigerant at you.

86 951 Driver

How much would a shop charge to replace that switch and recharge the system?