I am sure this has been worked thru before but can't find a way to search the threads.

I have a 2002 f150 4.6 Triton v8 with AC clutch not activating. I have the Haynes manual but I am finding the electrical doesn't seem to be accurate for this model.

I started with following the diagrams in the Haynes book by making sure I turned the key on set to max ac then verified I had 12v at the over pressure switch (pass side in front) and at the cycle switch on the accumulator, I jumped the cycle switch pins but the ac clutch relay would not activate.

I verified the fuse 5 (15A).
I swapped the 204 ac clutch relay with 205 horn relay and the horn worked before and after but still no ac clutch.
I jumped the 204 ac clutch relay contacts to try to activate the clutch and it did click (did not run because truck is only in power on not motor running condition.
Tried to do a continuity check from the output of the cycle switch and the 204 ac clutch relay had ~ 600 Ohms resistance .... so I removed the ground on the battery and opened the fuse box but the wire colors did not match the the diagrams or what was on the cycle switch.
Without having accurate diagrams I am in trouble now. Can anyone out there give guidance? I don't see any connection with a computer module and I do not have any codes stored.
I also did test D502 the ac clutch diode.

So I know the
over pressure switch is good
cycle switch is not the problem
ac clutch relay and diode is good
ac clutch is good.

This is obviously wrong...


but the ac clutch does not work driving down the road. what am I missing and does anyone have a diagram that is more accurate than the Haynes book?

 

If it was mine I would unplug the connector at the AC clutch solenoid, bring it up where you can handle it and connect a test light or meter to the plug. Start the engine and set the controls to where the AC compressor should come on. See if power is being sent to the AC clutch. You should get light or a voltage reading. p.s. a click from the solenoid does not necessarily mean that the clutch magnets are being energized. Could be the clutch magnet windings. (p.s. 2 I might not know exactly how that solenoid and clutch work. Just saying that a click might not tell the full story.)

I read through your post but don't see that you showed whether or not you had power to the clutch when you should have it. Might be in your words but it's not clear. If you're getting power then the problem is in the clutch solenoid. If you're not then it's on the power supply side.

You didn't say either if it's ever worked correctly for you. Good luck.

 

Yes sir your point is valid I just tested in a slightly different way but I think you will agree it has the same effect. I started the truck with motor running I turned the ac on max, set on the coldest setting. the compressor was not running the clutch was not energized, I then pulled relay 204 (the ac clutch relay) and jumped the contacts to simulate the relay closing. as soon as I did that the ac clutch clicked and the center of the compressor started spinning and the engine slightly slowed under the compressor load.so the issue appears to be before the relay 204 (the ac clutch relay).

Thank you for pointing out i had more I should have tested.

Any other ideas? I know I am stumped.

There appears to be something between the cycle switch and the ac clutch relay because the wire colors change but I can't find a drawing that shows it.

 

And sorry but the AC has worked without issue for years this is new this spring.

 

I'll send some 2003 wiring diagrams in a minute but in the meantime, it looks like the PCM controls the AC clutch relay by grounding it. So if jumping the relay pins works that means the PCM is not doing it's thing or there's a break in the circuit from the relay to the PCM. In 2003 it's PK/YE which I think is pink with yellow stripe. It says 69 C175 at the drawing. Might mean pin 69, I don't know.

Images coming...

 

These might help. Keeps me tuned up on reading Ford's odd schematics.

 

Looks like the two pressure switches tell the PCM that it's okay to energize the clutch relay. So those two pressure switches might be where to look. A guess.

 

Thank you for the diagrams ... Yours show the pcm having an output that can control the clutch, the Haynes only showed the pcm getting an input and that made sense to provide an idle up when the compressor is running.
but your diagrams show the pcm output to provide a ground for the ac clutch relay coil, I will try to track down the inputs that may cause the pcm not to enable the Relay to fire. also your wire colors match what is in the truck. That is helpful. Thank You!

 

I'd put a gauge set on the A/C
Chances are, you are low on freon or the pressure cycling switch on the accumulator is no good
You generally jump the cycling switch to verify the compressor runs, then check the refrigerant level