My buddy has a 96 Cherokee 4.0 and I cant get the AC compressor to kick on. I have checked the compressor relay and fuses, and jumped the pressure switch, it has refrigerant in it and it will come on and cool if I put power to the compressor clutch wire. I am thinking about just hooking up a toggle switch to the compressor clutch wire so he can turn the compressor on manually. The electric cooling fan also will not come on but he already has that ran to a toggle switch.

 

How did you test the relay? Did you verify that you have power to the relay socket where you should? Same for the fuse - how did you test it, and did you verify there is power at the socket?

How did you test for power? With a meter? Or a test light? If there is corrosion in a circuit, a meter may show full voltage, but the corrosion will now allow enough current to flow to operate things. Check with a test light.

Time to start circuit splitting. This is a troubleshooting technique where you lay out the circuit (in your mind, at least, better yet on paper) and start testing in the middle. For example, the start of this circuit is the battery, the end is the AC compressor? Where does it go in between? Find a halfway point and test. If there is power there, make that your new starting point, and go halfway between there and the compressor. If that new test point is good, that's your new start point. If it's bad, go back. Get the idea? It doesn't matter if you are exactly halfway. In fact, actual distance doesn't matter much - no need for a tape measure. You are testing it functionally. So, if there's a switch, then a relay, then a load, the relay is halfway, even if a measuring tape says it's 3/4 of the way.

Also, see my sig, #1.

 

Do you have power to the pressure switch? And if so does it come on when you jump across the switch?

 

A low charge or too wide an air gap between the clutch and compressor are possible.

 

I am not getting power to the control side of the relay. I am testing with a meter. A good wiring diagram would help.