AC questions

[nono54]

hi there ,
think I found out the reason why I did not have AC
the green cable that go from the AC temperature switch to the compressor clutch does not carry current ( maybe cut in some place!!!) tried with a new cable over the car and clutch does engage.
now the question:
1)the actual switch doesn't seem to have an off position is it normal?

2)how do I bring the green cable from the switch in the cabine to the engine compartment at the clutch?

3) my AC hoses are hanging on the left side of the car shouldn't they be hidden
and how and where to hide them?
thank for your input
Arnaud

[ChkbookMechanic]

(1) The temp switch does have an off position (all the way to one side, can't remember if it is left or right). You can use a continuity tester to verify this.
(2) haven't traced the wire all the way to the back, but it goes from the cabin to the smuggler's box then to the rear of the car.
(3) The a/c hoses aren't hidden, they are left out to the elements.

On my '84 the power to the compressor clutch goes like this:
fan switch -> green/white wire -> temp switch -> green wire -> smuggler's box plug -> green wire -> compressor clutch

I'd use a continuity tester between the green wire out of the temp switch to the wire connected to the compressor clutch to really make sure you have a cut wire. To perform continuity tests I'd do:
(1) between the fan switch and temp switch
(2) the two wires on the temp switch
(3) the green wire at the temp switch to the green wire plug in the smugglers box
(4) the green wire on the plug to the green wire near the compressor clutch.

Then you can tell exactly where the issue is.

If you have the Bentley manual for your car look at the wiring diagram and that helps a lot.

Good luck.

[Barrpete]

It sounds like your temperature switch is not working. It's designed to cut off the compressor based on the evaporator temperature. There is a long capillary tube filled with an inert gas that opens/closes the switch. If that tube is broken or kinked it will shut off your compressor and the compressor will not operate. The contacts inside the switch could also be dirty and have the same effect.

[nono54]

1)so if I jump the temp switch should that engage the clutch.
2)also when I was trying to read the diagram the green cable was going straight to the compressor and to the cooler fan wich mine is in the rear left fender and the fan switch had a cable going to the resistor,isn't it, will have a look tonight, will let you know
thanks

[Barrpete]

1) Yes. If you bypass the temp switch by jumping the two wires and the compressor kicks in then your temp switch is not working.

2) If you have a condensor and fan in the rear left fender your system has been modified.

[JFairman]

The capilary tube is inserted in between the tubes or rows and fins of the evaporator about 2-3 inches.
The tube is filled with freon gas, probably R12, and as the evaporator gets colder the gas contracts and that moves the points in the switch away from each other and depending on where you have the knob turned to that turns off the compressor till the evaporator warms and the compressor cycles on again.

If it switches off too soon, even with the temp knob turned all the way clockwise, then sliding the capilary tube part way out of the evaporator so only around an inch is into the evaporator fins that may help.

[nono54]

could it be because it is a euro model, the dryer is also there, on the front of the rear left wheel
and how did they originally bring the cable from the front to the rear of the car thanks
Arnaud

[JFairman]

Any AC hardware in the left rear wheel well is aftermarket. Porsche only installed the receiver dryer in the left front fender well behind the tire so it is closer to the evaporator, and can be installed in the high pressure line coming back from the front nose condensor and then goes to the x-valve and evaporator.

The wire that goes back to the compressor is in a wiring harness that travels back through the center tunnel then comes up into the engine compartment at the rear firewall bulkhead.
You can see the thick wire harness from under the car where it comes out of the center tunnel and travels up above the transaxle.

Then you can see where the wire comes out of the harness next to the right rear upper shock mount, and then travels down along the top side of the right longitudinal under the oil filter and hooks up to the compressor with a single spade termninal.

I'm not sure if the water sheilded spade terminal is origonal... that connection gets wet when it rains or you wash the car and may get changed as compressors are replaced.

[ruf-porsche]

There are a couple of relays that controls the power to the evaporator fan, front condensor fan and the clutch for the compressor. You could have a BAD relay.

[nono54]

hi guys,
so after couple of hours I trace back my problem;
the green cable wasn't cut , my drier receiver seems to be powered by the green cable and apparently it is dead so i jumped the electrical connection and it seems to work .at least i have current to my clutch and cooling fan
now I am wondering if the drier need to be changed and the whole system recharged?
or I leave it like that

I still wonder if the temp switch should turn the system off when fully counter clock wise or it only turn it off with the thermostat

Have any one seen a powered drier??????? is it common??????
thanks
Arnaud

[JFairman]

"Have any one seen a powered drier??????? is it common??????"

Someone installed a dryer with a pressure sensing switch on it.
Thats not origonal but it's an improvement and makes the system safer for itself and you.
The pressure switch turns off or interupts the power to the clutch on the compressor if the high side pressure gets too high, and some switches will turn off the compressor when the pressure is too low and there is not enough refrigerent in the system.

[Barrpete]

Originally Posted by nono54

hi guys,
so after couple of hours I trace back my problem;
the green cable wasn't cut , my drier receiver seems to be powered by the green cable and apparently it is dead so i jumped the electrical connection and it seems to work .at least i have current to my clutch and cooling fan
now I am wondering if the drier need to be changed and the whole system recharged?
or I leave it like that

I still wonder if the temp switch should turn the system off when fully counter clock wise or it only turn it off with the thermostat

Have any one seen a powered drier??????? is it common??????
thanks
Arnaud

SOunds like your system may be low on refrigerant. Might be time to have that checked.

The temp switch only turns the system off based on the evaporator temperature. There is not a full off function to it.