Gentlemen!
Went to use the A/C in my 00 V-10 Exc. for the first time since last year, and it never got cold (Worked great last year- ice cold)
Checked all the usual suspects (See below for specifics) the actual A/C componentry is fine. Long story short, it seems that the compressor is not getting power. If ya hot-wire it, it works perfectly, blows nice and cold. But just turning the switch on in the cabin.....the compressor does not come on (except for the briefest second).

What I had checked:
Freon. High pressure switch, low-pressure switch, relay, clutch- all good.

I've had two different shops look at it...no one can figure it out.

HELP!

(One shop- the oldest and best A/C shop around, got a reading on their scanner that the CHT sensor (Cylinder head temp) sensor was "out of range" and thought that maybe since that was the only thing they could find wrong, it might be worth replacing, as it might be triggering a signal to shut down the compressor, as if the truck were overheating- but I don't have any confidence in that being the case- as there are no other codes; no false overheating, no check-engine light, etc. -But I just thought I mention it to see if anyone's heard of such a thing, But I don't want to just start throwing money and parts at it for nothing.)

 

What connection point are you "Hot Wiring" it?

 

You're likely going to need to use a capable scan tool or equivalent to effectively diagnose. This is a PCM-controlled A/C clutch arrangement. If the PCM ain't happy, the A/C won't work. If you have certain issues related to the engine's operation (faults related to misfires or overheating, for example), A/C is disabled. Fix those first!

Is the PCM seeing the A/C Request signal (series circuit of CJB fuse F24, mode switch, low pressure cycling switch, & high pressure cutout switch ?

Is it issuing the signal to activate the A/C clutch relay (which, in turn, powers the actual clutch)?

 

The shop did that, so I'm not sure. (Nice Ex. ya got there!)

This is what the shop was thinking. Only thing their scanner was picking up was the CHT sensor being "out of range"- but since it wasn't triggering anything (Not throwing any codes, etc.) it doesn't sound like it's triggering any event to start shutting things down- but we all do seem to agree that it's PCM related- I just don't know of anyone 'round here who's got a dealer-level scanner and who knows how to use it well. I'll hook up my own scanner later just to see what it picks up....

Thanks for the replies, guys.

 

Forscan with a decent OBDII adapter will do the job.

 

Sounds like a wiring/harness issue to me if you don’t have a CEL

 

If it's an OBD1 calibration, many faults are non-MIL.

The absence of the "Check Engine" light is not indicative of much except that the brain-damaged calibration hasn't detected a severe enough fault to turn it on.

 

Is the PCM the thang located right against the parking brake pedal bracket? If so, this is beginning to make sense, since I changed the PARKING BRAKE CABLE a few months ago - Maybe the dern thing just needs to be jiggled! What sucks is, the A/C shop sucked the freon out of the system, so I'll have to charge it up again to play with it.....

SHO, whadduya mean an OBDI calibration? I'm not "getting" this, as an 00 is OBDII....but these electronic engine controls ain't my thing, so maybe I'm missing something.... And if it's not detecting something big enough to trigger the CEL (You know those CELs are SJWs- so easily tribbered! ) would it really be triggering enough doo-dads to start shutting things off, even right at start-up? (Not doubting you...just trying to learn).

Thanks for the replies.

 

A 2000 (non ATC) year should not be relying on the PCM..??? Direct operation via the dash controls?

Edit, looks like the PCM is completing the circuit.

 

Negative. Consult documentation.

Maybe, maybe not. You have to look at the label (documentation) under the hood to know for certain how it left the factory.

Vehicles under 8500 GWVR were required to be OBDII beginning in 19996. Over 8500# were not required to be OBDII-compliant unless they were originally sold into one of the named "green states". That exception continued for many years (more than 10).

Go read this thread for background, if you wish: https://www.ford-trucks.com/forums/1...bd1-obdll.html