international ac problem

Paging @Heavyd

 

I'm not an expert but that TRI something switch on the firewall controls the power to the clutch on the compressor. The cap on top is a ##### to get on. Try turning on the AC then push down on the top where the switch is and see if it starts the compressor.

 

There are two relays that are involved in sending power to the a/c compressor. The first relay is called "A/C control relay" and sends power forward when the a/c switch is turned on in the dash. Power for this relay comes from breaker F1-B, 10 amp. After that the second relay is called "Air Condition". Power to this relay must go through the freeze switch or thermal switch first. In order to help you better, which relay are you specifically talking about?

 

Ok, the air condition relay is a bit tricky. Power is normally routed straight through it from 30 to 87A to power the compressor clutch. When this relay is triggered from 85 it actually kills power to the compressor. Having no power at 85 is actually good because this is normal. If you have power at 85 it means the high or low pressure switch has tripped. In between the ac control relay and air condition relay is that freeze or thermal switch mounted near the evaporator. You should have access to it if you remove the side filter cover. The freeze switch has a sensing probe lead that goes into the evaporator core and is mounted near by. You should be able to see two wires connected to it. If you jump the two and the system starts to work you know your freeze switch is no good. If you jump it and still nothing then you have a wiring problem somewhere.

 

No problem, glad to help! Aren't trucks fun?