Hello, I have a 2006 XLT 4x4 5.4L with manual air conditioning. The AC compressor doesn't run. I removed the plug from the clutch and using my Ohmmeter determined what wire was hot and which was ground. When I applied 12 volts directly to the connector the clutch would engage. After a few more minutes and a look in the manual I am now at relay 203 in the power distribution box under the hood. On this relay pins 1&2 feed the relay coil and pins 3&5 feed the AC clutch. I checked fuse 17 and it was good. I placed a 12 test light across pins 1&2 and cycled the climate selector switch in the cab from off to AC. The test lamp followed the on/off sequences of the selector switch so I knew the signal side of the circuit was good. When I check for continuity from the AC clutch back to the relay I found that pin 3 on the relay was connected to the clutch. Does anyone know where pin 5 goes? I have seen an F150 schematic and it shows shows pin 5 as ignition hot, but I have no voltage present at any time.

I didn't check the pressure switches because I was assuming they were on the signal side of relay 203 and that part of the circuit was functioning properly. Does anyone have a schematic of the manual air-conditioning circuit for a 2006 F250?

I think I may have a broken wire somewhere. Thanks for your help.

 

Before you dig too deep, check your pressure switch. The system is designed to disable the clutch operation if the refrigerant level is too low. This protects the compressor. You may have a refrigerant leak.

 

Also, don't rely on the vacuum test most AC shops do to test for leaks in the system. They can give a false negative if the seals in the compressor itself have failed.

 

I found a wire somewhat exposed under the Power Distribution Box. It had a small cut/slice in it. There was a generous amount of the green corrosion in the area of the damage. I cut the wire, stripped off a little insulation, soldered and heat shrunk the repair. Now the AC runs properly. It looked like the problem was there for quite a while. Thanks for your input.