Ac Not Working Going Nuts

[bkenney]

Hi there. I've got a 06 silverado with a 5.3.

The only way I can get the ac clutch to kick in is to jump out the compressor relay at the engine fuse block. I've checked all fuses and have jumped out pressure switch by canister and by compressor. Also checked freon level and there is plenty in there. any ideas?

Thanks

[bill190]

There could be too little refrigerant or TOO much. The high/low pressures should be checked.

 

Then other than that, you would need a GM factory wiring diagram for your specific vehicle (in GM service manual set) and a multimeter.

 

Then start checking the circuit at various points.

 

You need the factory wiring diagram because it tells you what all is in the circuit. And the wiring is all wrapped up in harnesses and concealed in many places. So you also need it to show you where various connectors and components are located so you can test the circuit at various points.

 

And you need to know which pins on the connectors are for what, what wire colors on a specific harness are for what. The GM factory wiring diagrams show all this.

 

Then you need to know in some cases how to test various components or wires. The service manual troubleshooting section will say how to test and tell you what the reading should be. For example measure voltage or measure resistance.

 

Now a hint on the newer vehicles. There are sometimes 24 different computer modules on these which "talk computer talk" to each other over two or three different computer local area networks.

 

The computer network wiring will be shown in the electrical drawings with a sideways figure 8 around two wires or a half a figure 8. That means the wires are twisted computer wires. Or will show what looks like a can around a wire or wires. That means they are shielded computer wires.

 

Anyway those wires do not have a "voltage" as such, but send data which you can't see with a multimeter.

 

So stay away from those wires, but you can test with a multimeter the wires connecting to an electronic module. And you can test an electronic module to see that it has power.

 

The way this works is you have a switch in the cab. and this would go to an electronic module in the cab. Then that module would send a computer message to another computer module which would turn on a device like the A/C compressor.

 

So you can check the wires from the switch to the first module. Then check the wires from the other module to the relay, switches, compressor, etc.

 

And because there are so many modules involved, it is a good idea to check all fuses inside and under the hood. How to check fuses...

http://www.dinosaurelectronics.com/Test_Fuse.htm