1988 Carrera Power to AC compressor clutch

[MOP]

Can anyone help me locate the thermoswitch and high / low pressure switch that allow power to the AC compressor clutch?

[FrankM_]

Both in the mid console:
The thermoswitch is in your mid console and has a feeler to your heat exchanger in the smugglars box.
The other switch is the one next to that in the mid console providing power to the ac system (and setting the fan speed).
The relay is also in the smugglars box.

Standard a/c : there is no high/low pressure cutout. (at least on my 1985, I do see it on the 1988 schematic - possibly near the receiver / dryer in the left front wheel well)

There is a wiring diagram here for a 1988 : http://www.911c1.de/porsche/Schaltplaene/plaene1-10_carrera_32.pdf

It's in German (what else), see sheet 4 'Blatt 4', 'Kälteanlage' (right top corner) for the AC (M559 option code)

[GH85Carrera]

The factory stock delivered air cooled 911s did not have a high low pressure switch to control the compressor. They system was happy to run with no refrigerant and destroy the compressor.

If your system was update to use 134a it is possible they added a pressure switch. The compressor gets power from a wire that soulud come from the right side of the engine.



This is my setup but I have the dual condensers in the rear wheel wells both have fans, and I have a pressure switch on the hose. The wire to run the compressor should be a black wire.

[Peter M]

An aftermarket trinary switch is most likely fitted to the high side charge port on the compressor or a port on the receiver/dryer that located in the LHS mudguard.

They can also be fitted to a special "charge port" hose fitting that has been spliced anywhere into the high pressure hose as well.