79 Series 2010 V8 Turbo diesel A/C issues

[onthemove]

First let me apologise in advance if I am covering old ground here. I have only just joined the group. The a/c in the Cruiser has stopped working. The fan runs, there is gas in the system, and a mechanic I had check the issue told me there was a circuit across the LP switch. He spent 2 hrs on the problem and then gave up. In fairness we didnt have a circuit diagram too go by. The magnetic clutch wont engage. I am looking for the water temp cut out switch, but cant locate it. Can anyone help me with which terminals I need to bridge to test the clutch operation, and where these terminals are located? Or better still, where the cut out SW is.
Regards

 

[StarCruiser]

If you separate the connector at the clutch and take a wire to battery positive and touch it on briefly for test purposes, the clutch should kick in. If you can’t get the compressor running, how do you know it has refrigerant in the system?

 

[onthemove]

We put refrigeration gauges on the system. There is enough pressure to enable a test run. Unfortunately the plug for the clutch is located in a spot where you cant even see it, let alone connect a temp supply. thats why I,m hoping to find a terminal upstream that will feed straight too the clutch.

 

[Firewout]

In the hzj 75 and 78, you can bridge the cutout switch in the connector at the ac amplifier behind the glove box.
At this connector you'll have access to the clutch wire as well.
I guess the ac setup in your 79 won't be that much different.

 

[onthemove]

I have done a continuity check on the cable from the clutch too the amplifier. It is open circuit. There is a set of contacts somewhere that are open. Buggered if I can find them. When i start the fan, you can hear the engine revs are up. After about 3 seconds they drop back to normal idle. It's like a relay comes in on fan start and then drops out again.

 

[StarCruiser]

If you can get to the LP switch, unplug and temporarily bridge out the wires and see if that does anything. Sometimes you can get continuity through a switch that won’t take a load.

 

[onthemove]

Thats a great idea. Now, can you tell me where the LP switch is located?

 

[Firewout]

switch is marked in blue

 

[Firewout]

 

[Firewout]