Hi Everyone,

I'm troubleshooting an A/C issue on my 2006 e-250 5.4L, with front A/C only. While reading this post please keep in mind I'm a novice mechanic, especially relating to vehicle electrical circuitry. Anything usually assumed to be known... I might not know and may not have tried.

The connection to the compressor has 2 wires, a hot and a ground. The ground is tested and working, but no power to the hot line. I have already hotwired the compressor in order to manually fill with refrigerant in order to activate the low pressure switch (I found out afterwards that this can damage the compressor). The A/C clutch engages when power is received and the vents in the cab blow nice cold air.

I found power being delieverd to the low pressure switch and also jumped the low pressure switch and checked for power at the compressor (none there). I've also replaced the A/C relay ($20! should have just tested it...) and tested the PCM relay.

I've also tested every single fuse in the van (fuse box under steering wheel, power distribution box under hood driver's side, relay box above master brake cylinder). I'm pretty sure I tested and/or replaced the relays correctly. The fuses were easy to test.

I believe I have power at the PCM relay, and the A/C relay, but I'm not sure if I'm testing just the control circuit pins. I'm confused by where the compressor directly gets power, because the wire disappears into a harness which wraps around the entire engine and then plugs into the brain (engine computer?). If anyone has any advice or wire diagrams, please let me know! I need to know which other components are involved in this circuit and what I should be testing. I haven't messed with anything in the dash yet because I think it is vacuum controlled and looks scary, AKA I don't know what to test. Hopefully I'm not missing any diagnosis information, please ask.

Thank you for reading!

-Ryker

 

Have you scanned the PCM for any DTCs? This is a PCM-controlled system. Certain faults will disable the A/C system due to PCM programming.

Does the AC clutch relay click (or not) when the climate control **** is switched between OFF and one of the modes where compressor is supposed to operate (engine running)? You may need to have an assistant operate the **** while you place a fingertip on the relay to see if you can feel it click.

 

I haven't been able to check the codes because of the Corona Virus pandemic. The auto stores aren't doing scans. I should try a mechanic shop.

With the A/C control on MAX A/C I disconnect the connector from the compressor and test the ground and hot wire in the harness. Ground is working, no juice on the hot line.

Edit: I have hotwired the compressor and applied power and ground to the compressor. It clicks on and cold air blows from the vents.

 

The auto stores would only be able to do a cursory scan. You'd be well advised to order in an OBDII adapter and make a small investment in what you need to become self-sufficient. Otherwise, you're flying blind unless you hire out the diagnosis and repair.
You're repeating yourself as all of that was in your initial post. None of that addresses or answers the specific questions asked. This does not bode well if you cannot follow directions....

 

Sorry for the disoncerted answer. What I mean to say is that no, the A/C compressor does not click (engage) when the climate control **** is switched between off and A/C with the engine running.

 

My question was about the AC clutch relay, not the "compressor".

 

Facepalm... oops. I should have read that more carefully, thanks for clarifying instead of giving up on me! I just tested to see if the clutch relay would click when the A/C was activated via the control panel, and it does not click! I'm not sure if this means that the PCM is not sending the signal to the relay or if the PCM is not getting the signal at all. Please let me know what you think and where I should go next... In the mean time I'm purchasing a scan tool.

 

Had the OBD scan done, only p0355 code. Which is weird because this van has always had a bank 1 lean and bank 2 lean code since I bought it a year ago... I did have the battery unplugged today but only for 30 seconds or so. Perhaps that was enough to reset the code... I'll have to look into this more.

 

To that point ProjectSHO89----if the PCM has disabled the compressor would the dash CEL lamp indicate there are DTC's present? ( have none at the moment, will scan the PCM when I begin digging into this.)

I'm facing this same situation and will begin by checking fuses associated with the compressor circuit including the relay---have the Ford EVTM's for my year. IF there is a DTC disabling the compressor is there a common code and what possible fix might exist?

TIA

 

Fix the P0355 fault first. That code indicates that the #5 COP circuit has an issue and you'd be expected to be running on one less cylinder than normal.

I've never seen a listing of DTCs that will disable the A/C compressor, but I do know that a severe misfire condition is one disabling condition. The factory service manual simply includes the following as part of the preface to the pinpoint for "No A/C" diagnosis:Those are explicit instructions that, if ignored, will lead to waste of time and money.

 

Fix the P0355 fault first. That code indicates that the #5 COP circuit has an issue and you'd be expected to be running on one less cylinder than normal.

I've never seen a listing of DTCs that will disable the A/C compressor, but I do know that a severe misfire condition is one disabling condition. The factory service manual simply includes the following as part of the preface to the pinpoint for "No A/C" diagnosis:Those are explicit instructions that, if ignored, will lead to waste of time and money.

It depends. Not all DTCs will set the MIL on all platforms. For example, there are multiple possible faults on my era of SD that will not not set the MIL to on due to its OBD1 calibration.

 

I do have OBD-II and as I mention schematic shows the compressor being controlled by the PCM----thanks for the clarification though. There is only one DTC that referenced my catalytic converters were or had been operating below efficient threashhold----when that first appeared the van had been idling for probably 5 hours or so. That code has since been cleared.

Well as it turns out I've discovered my problem---absolutely no refrigerant in the system. Seems some months ago I lost a 3/4" wrench and found it just a short while ago---wedged between the condenser and grill, worn a hole which naturally is the leak.

Have a new one on order, great to have friends in the business----$104 my cost.

Thanks pSHO!

 

Hi SHO89!

It's been a while, but I've finally made some progress. I was able to resolve the P0355 by replacing the ignition coil on cylinder 5. After clearing the codes from the PCM, wala! The AC compressor clutch is now receiving hot to engage and the AC blows cold. However just a few miles later, the new ignition coil blew! What a bummer, but I did buy a cheaper one at $30 from Oreily. Tried another ignition coil, it worked. Blew again within a few miles. Tried a third, blew within 1 mile. I did test these last 2 ignition coils to make sure they were working before installing them. I removed the igntion coil and boot but left it plugged in to the wiring harness and put a spark plug in to the end of the boot and put the plug next to something metal while started the engine and I could see the spark. Something is blowing my ignition coils up quick. Also noteworthy is I've tried different brands of ignition coil each time. The last 2 being blue *something* and the final being duralast which I currently have installed in cylinder 4 with no issues after 5k miles. When these coils blow, there seems to be some melted plastic towards the bottom of the cylinder near the seam / right angle, on the backside. Same spot in 2 of the ignition coils.

The AC is intermittent during this process, but is no longer my focus. I've replaced the plug with motorcraft platinum, verified the plug gap and the electrical connector to the ignition coil. I'm receiving constant hot and flashing ground to the ignition coil when tested briefly. I haven't tested extensively to see if constant ground is being provided at some point and burning up the ignition coil. My suspicion is a crossed wire somewhere up the harness or a bad PCM. Any ideas? Thanks again for all the help you've provided so far!

I'm a noob around the forum but I'm thinking I should make a new thread regarding my p0355 issue?

-Ryker

 

Found 2 bare wires crossing I the wire harness not too far from PCM up agains the egr tube. Repaired and solved p0355 and AC blows cold.

 

Good job.

Without specifics, my take is that one of those wires was the coil driver for the #5 COP. When the bare wire shorted to ground or wherever, it forced the coil into a continuously "on" state, something it wasn't intended for, and that caused it to fry from the continuous current through it.

Did you by happen record (or recall) the wire colors of each wire?