I started to look at my compressor wiring today because I was going to jump the compressor clutch to see if it engages before I take it to the AC shop to get it charged.
Upon inspection (see pictures attached) I have the following:
Green aand black wires connected to the front of the compressor for clutch operation.
Black wire connected to the back of the compressor. I guess for the pressure switch
The above wires are connected to a 3 pin connector which plugs into I would assume is a thermal limiter.
However, the green/brown wire in the 3 pin connector is not connected to any part of the electrical harness.
As it stands, all wires are connected to the compressor, but not to the harness of the car.
Seems to me, that the green/brown wire needs to be connected somewhere, to power the compressor circuit.
Looking at the S57 diagram, it is showing this hanging wire for the earlier cars
The diagram also shows the this green/brown wire should be connected to an anti-ice thermistor on later model cars.
Seeing that I have a thermal limiter or so I think, where or what does this green/brown wire connect to?
I have searched high and low to find the power source for the compressor and there is nothing in that area. I am at the point where I am going to remove the windshield washer bottle to see if there is any connector snagged behind there.
Is it possible for someone to post a picture of how theirs is connected?

 

oops another pic

 

The green/brown wire travels around the front of the cylinder head just below the round breather cover....and is often tied to the fuel return pipe....itself uually obscured under a heavy crust of gunk. It's probably broken and dangling in that neck of the woods. Sometimes it take some real searching to spot it (ask me how I know!). I've seen a number of them broken.

It ultimately drops down in the area of the distributor and then attachés to the car harness on the RH inner fenderwell, down low...just forward of the shock tower. The car harness has a multi-pin connector but the a/c wire juts out of the loom all by itself.

While you're rooting around up there, replace the 2" long piece of fuel hose at the front of the cylinder head. It is a joiner for the two sections of fuel return pipe. This is often neglected as it is well hidden

Cheers
DD

 

you can look at my connections, they are stock other than I added a wire for summer use to keep the aux. fan running, but which is easily disconnected.

 

THANK YOU DOUG. The G/N wire was hiding in plain sight, just where you said it would be.
Question: Does the Thermal Limiter need to see a signal from the pressure switch (Black Wire) from Thermal limiter to the rear of the compressor, in order to send power to the green wire (Thermal limiter) to the compressor clutch?
I now have 12 volts at the G/N wire on the Thermal limiter, but no power thru the Thermal limiter to the Green wire which goes to the compressor clutch.
Applying 12 volts directly to the green wire, activates the clutch.
Is it wise to bypass the Thermal limiter if it is faulty? Not sure how it works.
Thanks again.

 

It isn't a pressure switch, it's a 'superheat switch'. From memory it grounds when closed, which blows the thermal fuse....which of course interrupts voltage to the clutch


I'd say the thermal limiter/fuse is blown....likely from lack of Freon.

I wouldn't bypass it for long as you're defeating the protection circuit


Cheers
DD

 

I received a new thermal limiter today. Before I install it, I used my voltmeter to compare the old with the new. On the new, I have continuity between all three terminals.
Is this how this thermal limiter is supposed to work?
As it is, If I put 12 v to the center terminal G/N wire I have 12 volts at the green wire terminal that goes to the clutch and 12 volts at the black wire that goes to the superheat switch. Is that correct?

 

Continuity between all three posts is normal when the fuse is not blown. I can't remember, offhand, which posts go 'open' when the fuse blows.

All my notes and diagrams are still packed away from the move. I'm living in a sea of cardboard boxes right now

Cheers
DD