Like the title says I am dealing with an 01 F 150 it has the V6 and the AC just quit working all together. I replaced the heater selector switch in the dash and still nothing. I jumped over both of the switches under the hood to see if it would pull the clutch in and it didn't. The fuses and relays are all good. The fan motor blows but no cold air. I tested the plug on the compressor and there is no voltage there when the selector is on max AC with the engine running and fan blowing. What am I overlooking?

 

How it works, for one.

Have you checked clutch gap?

Have you made any voltage checks any other place than at the clutch connector?

Have you verified relevant fuses and relays?

Do you have the schematic so you understand what is supposed to be where?

 

I haven't checked the clutch gap yet. It never quit here or there like they usually do whenever the clutch is going bad. It just up and quit. We did replace the heater selector switch. The compressor was the only place I checked or current. Yes the relays and fuses are good.
Bill Vose sent me the schematic. I have looked at it a little , but not thoroughly. I thought for sure there might be something problematic with these so that's why I posted it here.

 

compressor won't com on if low on 134 .Or if a pressure switch is bad . Or a wire broken ....... and more .

 

Right, but wouldn't jumping across the low pressure shut off by pass that?

 

Now I don't understand 100% as far as how it works goes. However, I am pretty sure if there is no voltage present at the plug going to the compressor that the clutch gap is completely irrelevant at that point correct?

 

yes, you need voltage to the clutch to make it work. If you jumpered the low pressure and high pressure switches, you should have voltage to the clutch.... unnless a fuse is bad or wire broke.

 

No . As Steve ( ill) pointed out , there are more things in play than just the low pressure switch . Relays , fuses , High side switch , ECM signal to relay , wiring . You need to follow the schematic , pinpoint test all electrical components , not just at the compressor .

 

Run 12 volts to the compressor with a jumper wire. If it works then you have to track down an electrical issue, which that's what it sounds like so far.

 

If you jumper 12 volts to the clutch silenoid and don't here it click in the clutch, the silenoid is bad. Just my opnion.

 

There's no such thing as a "clutch silenoid". It's simply a clutch coil.



You really need the electrical schematic in order to keep from wasting time and parts. In general, on an 01, the circuit goes something like this:

Fuse > Mode switch > Cycling switch > High pressure switch > PCM input as "AC_Request" signal. (switches might be reversed).

then,

The PCM, when it's programming permits it to do so, then energizes the clutch/WOT relay which then routes fused power to the clutch coil.

I don't have the diagram handy this morning, but that brief road map should give you an idea of where to take actual voltage measurements.

 

OK, gotcha.

 

Here is an update. There is a fuse that keeps blowin in the cab of the truck. I want to say its #5. As far as I can tell something inside the dash may be the culprit. Possibly the blend door actuator. According to what the fuse runs that has to be where the issue is. This truck has no daytime running lights and is a standard tranny so that eliminates the digital range whatever for the tranny. That leaves the speed control. We unplugged it and put a new fuse in it and it blew immediately. Then the heater selector switch is on the circuit and we just replaced it too and inspected the wiring as well. There is nothing suspect under the hood for wiring issues that is visible. Nothing looks melted or wrinkly. I am under the impression that the dash has to come off to see the blend door actuator and the rest of the wiring?

 

Fuse F5 supplies only two things - the blend door actuator and the mode switch circuit described above. Light blue/pink wire.

Unplug the mode switch and see if the short goes away. If not, you'll have to unplug the BDA to see it it is what's shorted.

The BDA is behind the floor duct. You don't have to remove the dash, but, if you have a center floor console, it has to be removed, then a couple of braces, the duct, and the RCM.

The blower circuit doesn't involve F5.

 

I don't see a lot of issues with the wiring in these trucks unless damaged by something . That said .. does it have any add on's ? aftermarket sound system ? I see a lot of aftermarket crap cause issues . Just a thought !