A/C trouble

So driving back home from a little road trip labor day weekend we stop and fuel up about half way home and I sense a little bit of a stumble or rough idle (this is my 3rd expedition so I am already aware that the coil packs go out in them). So Will keep heading home for a few more hours and then about 20 minutes from home the A/C stops blowing cold. We get home and late and I start diagnosing the next morning. I notice at start, up the compressor runs for about 5 seconds and then clutch disengages and she blows hot. i scanned the computer and got a P035 ignition coil D primary/secondary circuit. So to fast forward I have done the following, jumped the low side pressure switch still no clutch engages, jumped the clutch and she blows cold, changed the coil pack "D" #4 against the fire wall on passenger side. I can clear the code and check engine light goes off but the AC clutch still won’t come on then after a little bit of running the check engine light comes on and it starts stumbling again.
it is a 2003 expedition four-wheel-drive XLT 5.4 L. Manual controls for front and rear air conditioning.

I would appreciate any suggestions, I have read on one other form that the guy had a problem with his ECU and it was Still thinking he had a coil pack out and it was killing the AC.

Do you have a AC manifold and hose set that you can read the pressures in the AC system with ?
How old are the coils and sparkplugs ? All the coil connectors tight ?







.

Yes I have an manifold gauge set. 35 on the low side and 150 on the high but I have to put 12V to the compressor to get it to run so I can get a reading on the gauges. But I have jumped out the low pressure switch so if it was low on freon the AC compressor should still come on.

i’m not sure the age of the coils and spark plugs I’ve only owned the vehicle for about a year. I previously did one of the other coils about nine months ago.

I will check the coil connections on the other cylinders but I still keep getting the code for cylinder "D" even after I have changed the coil out and ohmed the wiring for that coil going from the coil plug to the computer.

What switch did you jump? 'Cause the low pressure cutout switch is in the expansion valve behind the PCM. Add a little freon to the system and see if the compressor will come on. If you don't know when the plugs were changed I would go ahead and replace them as well, so you have a maintenance base line. Inspect the coil boots and use some dielectric grease in the boots when you re-install them.






.

When I first started messing with it, It wouldn't take Freon unless I powered the AC clutch. So I did that and put some Freon in it and still the same problem persists. Yes I jumped the 2 wire switch that is in the expansion valve.

I agree could be a plug. But it still gives a code P0354 for coil “D" after I’ve changed the coil.

let me ask this, Coil pack "D" is Cylender #4, pasnger side all the way against the firewall right?

Yeah, should be #4 circuit. Do you have a test noid light ? You can check the signal to the coil with the noid light. But I would throw in a new set of plugs anyway. I hate to think a previous owner didn't replace that #4 plug 'cause it was too hard to get to and he was getting rid of the Expy anyway.






.

Apparently, the computer disables the compressor when it senses a misfire in the engine.
This was reported by another member in a thread. I also had the same happen to me a couple weeks ago. My # 6 coil has a bad clip on it's connector and backed out of the coil.
Started with a miss and no A\C. Found the problem. Plugged it back in, cleared the codes and all is good. A/C nice and cold.
Mike

I picked up a noid light kit today and spark plugs. I’ll se if I get time tonight to mess with it.

Ok so I hooked up the noid test light to the coil "D" #4 cylinder and I get no light lit up. To make sure the noid light worked I hooked it up to another cylinder and it flashed the light each time it fired that coil. Again, I previously have ohmed the wires that go from #4 coil pack to the pin where it plugs into the computer and the are good.

So I’m pretty sure it’s the computer now. I feel my next step is to order a engine computer.

May want to check and probe the wire to #4 as far back as you can, could be a bad connection/wire broken.