My ac was giving me trouble, wouldnt stay cold, so I sucked it out at work, and filled it up with the proper amount. Ac was cold as ice, worked perfect. On my way home, it gets hot. The compressor wont kick on now. So today, I figured it must have a leak, so I suck out the same amount that I put in yesterday, so its not leaking. I filled it back up, still doesnt work. No blown fuses, relay is fine. Power is getting to the pressure switches, but no power to the compressor. Jumping the pressure switch doesnt kick on the compressor either. Im lost now.

 

The wire from the relay goes to the A/C clutch, so is there a brake between those two points?

 

There is no relay in the truck's circuit. The clutch coil is switched directly by the cycling switch (which is why they fail so frequently).

If you have power at the low pressure cycling switch (both terminals), then you have an open circuit on the BK/Y wire that runs from the cycling switch to the clutch coil connector.

Steve

 

Steve, I think he is calling the A/C Clutch Diode a "relay".

 

Your diagram is NOT of a 98's system.

Ford has changed the system several times. It is important to use the correct EVTM.

The 1998's diagram is available here: http://www.mediafire.com/?gy915gtdshw

Steve

 

The '98 diagram is still showing a A/C clutch diode before going to the A/C clutch:

 

Thanks for that.

 

The diode is used in pretty much every Ford in parallel with the clutch coil. It really has absolutely nothing to do with the operation of the clutch, it's there to protect the electrical system of the vehicle from damage when the coil's electromagnetic field collapses by shunting the induced voltage to ground.

From the information given in the first post, it is impossible to determine he was actually referring to the diode, in any event.

Steve