Where is this AC temp switch located?

[billjam]

I am not getting power to my compressor clutch.
I have checked all fuses and components in my AC system and all seem OK.
Looking at the wiring diagram, it seems that the fault could be in the temperature switch.

WHERE IS IT???

Car is US model 1986 930.

[Mitch Leland]

Bill,

If you checked all the fuses, I would go for the relay in the smugglers box. It's on the right side wall of the smugglers box. It's a pretty standard relay.

Some one can tell you how to check it to see if it's working. You put 12V across two of the "correct poles" and you'll here the relay kick in. I replaced mine for the same reason about a year ago.

[TibetanT]

The "hot" wire coming from the battery should be terminal 30 on the relay. To complete the circuit, from this diagram, try 87 or 87b.

As mentioned, you will hear a click from the inside of the relay and that means the relay circuit is working.

If relay is working, as mentioned above, then move to next in line such as the switch on the console or rather inside the car. A voltmeter should be able to tell whether the resistance is up to par.

If switch is working correctly, move to the A/C compressor and try bringing 12V to it to see if it works.

If all of the above point to everything being operational, then you have a break in the wiring somewhere within the car.

If I have missed something here, hopefully an expert will chime in.

Hope this helps and good luck with your troubleshooting.

[billjam]

Originally Posted by Mitch Leland

Bill,

If you checked all the fuses, I would go for the relay in the smugglers box. It's on the right side wall of the smugglers box. It's a pretty standard relay.

Some one can tell you how to check it to see if it's working. You put 12V across two of the "correct poles" and you'll here the relay kick in. I replaced mine for the same reason about a year ago.

Mitch,
That relay only controls the main blower on the evaporator.
It is working OK. When I pull it, the blower goes off.
There is also no connection from this relay to the compressor clutch circuit.

[billjam]

Originally Posted by TibetanT

The "hot" wire coming from the battery should be terminal 30 on the relay. To complete the circuit, from this diagram, try 87 or 87b.

As mentioned, you will hear a click from the inside of the relay and that means the relay circuit is working.
If relay is working, as mentioned above, then move to next in line such as the switch on the console or rather inside the car. A voltmeter should be able to tell whether the resistance is up to par.
If switch is working correctly, move to the A/C compressor and try bringing 12V to it to see if it works.
If all of the above point to everything being operational, then you have a break in the wiring somewhere within the car.
If I have missed something here, hopefully an expert will chime in.
Hope this helps and good luck with your troubleshooting.

Ed,
All relays and the compressor clutch check out OK.
I haven't ripped out the fan speed control or thermostat in the center console yet, but the fan speed is working OK and the thermostat isn't directly connected to the compressor clutch anyway.

The only thing I can't find is the temperature switch.

Anyone know where it is located?

[TibetanT]

Bill:

Sorry about that.

I don't know exactly where this switch is located, but from the diagram it appears to be connected via a Green/White (size=2.5 guage) wire coming from the Air conditioner blower switch. ( If it is like my '83 SC, that blower switch is in the console, correct?)
My best guess now is that this switch is located inside the dash, or behind the dash inside the air conditioner air tunnel...that way it could measure/or rather sense the temperature of the air being blown into the cabin. Does that make sense. At least it seems to me this switch you are looking for measures temperature of the air being blown so it knows (senses) when it needs to turn off, or on.

I know on my 944, there are grounds connected under the dash near the fire wall for a common spot to ground all internal (cabin related) electrical connections.

Is there anyway you can trace the green/white (2.5) coming from the blower switch. Or, one of the brown (ground) wires? I'm thinking these wires run under the carpet up towards the front of the car and then up into the dash, behind the spot where the air vents are located (middle of the dash).

[billjam]

Yes Ed, figured out roughly the same idea, but when you work through the wiring diagram, this switch in the circuit operating the compressor clutch.

There's two options here - it is either a high temp shut-off or a low temp shut-off.
When it opens, it shuts off compressor.
I can't imagine it being for high temp, otherwise the AC would never start up on a hot day!

I can imagine this switch shutting down the compressor if the evaporator froze up, but there's no switch or sensor in there except for the capillary tube that runs to the thermostat. This is making me think that maybe the temp switch is closely related to the thermostat.

Looks like I am going in there next. I hate pulling out that console - too many wires and difficult screws.

[billjam]

FOUND IT!

I can't believe it, it is actually the temperature thermostat in the center console. Senior moment!

I never use this control - it is always full ON.
So guess what happened to its two wires? They are now the closest of friends!

[86 911 Targa]

Originally Posted by billjam

FOUND IT!

I can't believe it, it is actually the temperature thermostat in the center console. Senior moment!

I never use this control - it is always full ON.
So guess what happened to its two wires? They are now the closest of friends!

Bill,

If you shorted the temp switch wires together, (green & green/white), your compressor will run as long as your fan switch is on.

The purpose of the temp switch is not only to regulate the cabin temperature, but to prevent evaporator freeze-up.

You should replace the switch.

When you do, be very careful fishing the capillary probe through the firewall.

I replaced one in our 911 and it does take a bit of patience.

Also, maybe a case of Crown Lager..............

Cheers,

Gerry

[deshetlr]

Also, the new switched are slightly larger than original so you may need to do some minor surgery to the plastic housing.

[deshetlr]

Also, the new switches are slightly larger than original so you may need to do some minor surgery to the plastic housing.

[86 911 Targa]

Originally Posted by deshetlr

Also, the new switched are slightly larger than original so you may need to do some minor surgery to the plastic housing.

The Ranco switches are the same size, but when installed as per the original vertical position in the console housing, when the temp knob is rotated fully counter-clock wise, it does not indicate the minimun setting.

This is the case for the Ranco switches both dealer and after market.

Good luck,

Gerry

I have two tested 1986 switches if any one is interested.

[Vmarch]

Are you interested in selling the AC temperature switch?

[86 911 Targa]

Originally Posted by Vmarch

Are you interested in selling the AC temperature switch?

I would really prefer to bundle/sell all of these items together.

Listed on 911 used parts under central locking.

@ $100.00 for everything.

PM me if interested.

Gerry