I bought my 04 explorer Eddie Bauer 4.6 2 years ago. The previous owner rigged the ac with a hot wire running from the ac relay to the high pressure switch. Ac blew cold until it would ice up to the point no air would flow from the vents. The ac was constantly running unless I disconnected the wire from the relay under the hood. The compressor finally blew and I mean literally a gaping hole on the side of the compressor case.

I replaced the compressor, accumulator, and office tube and flushed out the lines In both directions. I pulled a vacuum and after several hours of holding vacuum I was satisfied there were no leaks and attempted to recharge the system but the compressor wouldn't engage. I've tried bypassing both the low side and high side switch, turning the can upside down to add as a liquid, and couldn't get the compressor to kick on to charge the system.

I started checking the electrical and found that I am not getting any power to the compressor at the wiring harness but the ground wire is receiving ground. I'm getting power at one end of the low pressure harness. I've checked the under hood ac fuse and switched out the ac relay but no luck. I read the FAQ section but didn't find anything that pertained to me. If anyone could point me in the right direction to get it running properly I would appreciate it.

 

You should also replace the condenser. A grenaded compressor will fill the condenser with shrapnel that cannot be flushed out.

You didn't indicate if this is a manual or an auto climate control. There are critical differences in how the compressor clutch is controlled between the two versions.

 

Do you have any idea why he did that and if it's reversible so that the wiring can be made right?

 

I'm not real sure how to answer projectSHO89. Mine is an electronic control that allows for different temperatures for passenger and driver.

 

I really don't know why that was done brother. The system is electronic and a bit beyond my understanding of how ac systems work. I've never worked on one like this so I'm stumped.

 

I didn't get to thank you both for replying but I do appreciate it.

 

That is the Dual Automatic Temperature Control version or DATC.

How it works (sort of, simplified version).

In a DATC system the climate control's computer decides, based on operator input, the inputs of various sensors, and its programming whether or not to request compressor operation. The DATC module then sends that request to the PCM as a message over the CAN network. The PCM then, under the control of its own programming and its own set of input sensors, either activates or deactivates the compressor clutch via the AC Clutch Relay. Simple, eh? Sheesh, you need to be a computer engineer to figure this system out....

To effectively diagnose this system, you really need a scan tool or equivalent (Forscan, for example) that can go in and read the status of various DATC module codes and PCM input and outputs status PIDs. Without this capability, "troubleshooting " is limited to a few checks followed by "guessing". So, what's your status? Do you have the capability to do that, or are you limited to voltage and resistance multimeter checks or just "guessing".

If you have the fullest capability, the easiest thing to do is simply pull out the factory procedure and post it but it assumes a trained technician with the correct diagnostic tools is following the procedure. If you fall into the middle category, I can provide some basic checks to make. If you're in that final category, I can provide a few observations you can make to to improve the odds of guessing correctly sooner rather than later..

LMK.

Basic things to do first:
1. Run the DATC module's self test. Report any faults. Google "Ford EATC self test".
2. Check for any PCM codes as certain system faults automatically disable the A/C system.
3. Check fuses that are critical to the operation of the compressor clutch: Fuses F37 under the hood (HOT in START/RUN) and fuse F10 under the dash (HOT in START/RUN). Do not rely only on a visual exam, also verify that the fuse is actually passing power when it is supposed to.

 

Great info brother. I have a fluke multimeter and a Matco MD 9001 scanner so I can pull codes and test fuse but I don't think I have the full capability of a more advanced scan tool. I checked the under hood fuse and relay, both checked out ok. I'll check the under dash fuse and let you know.

Thanks

 

Good news, the #10 under dash fuse was bad. I replaced it and was able to charge my ac and its blowing cold now.

I ran the EAC test and it checks out properly.

My only issue now is the that wire rigged from the ac relay under the hood. It makes the compressor run constantly and was freezing up the evaporator before causing a no air at the vent situation until I disconnect that wire long enough for it to defrost. I didn't run it long enough to know if it's still freezing up but I don't like running my vehicles with wires bypassed. I would like to identify the problem and address it properly.

I'm not sure if it means anything but I forgot to mention before that my ext temp has always been inaccurate even after I replaced the sensor in the front grill. It's currently displaying 93°when it's actually only 73° outside. I'm not sure if it would cause any issues with the ac but being that it's electronic and relies on sensors, I figured it was worth mentioning.

Thanks for all your help

 

Schematic of clutch control circuit is below.

The guy who used the high pressure switch to trigger the relay had it bass-ackwards. If you use the LOW-pressure cycling switch to directly control the low side (ground) of the clutch coil, one can bypass the whole computer control of the clutch although the PCM is going to be confused with its idle control strategy when the clutch is operated. This should prevent the continuous operation that leads to evap freeze-up.


Yeah, it's worth mentioning. It's may well be a factor in the improper operation of the system but I haven't dug into that before.

My recommendation is to first restore the wiring to original configuration and re-evaluate system operation. Trying to remotely troubleshoot a ba$$tardized, hacked system is pretty much futile.

 

Cool. I'll go through the wiring and get it properly wired. I'll update you once I pinpoint the problem.

Thank you so much.