Hey guys,
I kind of have a head scratcher for ya. I picked up an 03 navigator 32V with all the bells and whistles the other day because I need room for my growing family. I went ahead and tuned it up, changed the oil etc. The previous owner told me that the A/C needed to be recharged, so I hooked my gauges up to it. It was low. While I was under the hood doing the tune up, I noticed that the pressure switch on the expansion valve assembly was seeping oil out of it, so today, I went to ford and bought a new expansion valve assembly and Installed it. I changed all the o rings, added some oil to replace what had leaked out and sealed up the system. I ran my vacuum pump on the system until it was holding steady at 400 microns, and proceeded to charge the system. While I was charging the system, I had the truck running, and I noticed that even after 2 cans, the compressor did not cycle on which was weird to me because even though the system capacity states that it holds 54 ounces of refrigerant, I would have thought that the compressor would have at least cycled on by then. Well I was only able to get 3 cans into it before the pressure was equal between the system and the can. Even with 3 cans in it, I can not get the compressor to run steadily. I had my gauges on it so I knew I didn't overcharge it, but no matter what I did with the EATC, I could not get the compressor to run consistantly. The only time it will run is when I first start the truck, and it will run for about 15 seconds and then shut off. I was eventually able to finish charging the 54 ounces by starting the truck multiple times and letting the compressor run for its 15 seconds to drop the low side pressure and draw the refrigerant in. I jumped out the low pressure and high pressure switches, checked the fuses, and even tried a spare known good relay in the relay box behind the drivers headlight, but still it will only run for about 15 seconds immediately following the truck being started. If i remove the relay, and jump the pins out, the compressor will run indefinitely. The strange thing is when I put my multi meter leads on the pins for the relay coil, I am seeing battery voltage, but when I put the relay in, it will not click and pull in.

I am HVAC tech by trade, and years ago I went through the ford training program to be a dealership tech, but my specialty was heavy line and diesel, but thats not to say that i am not well versed in electrical.

My brains kind of boggled right now because I can not figure out why if all the pressure switches are satisfied, and theres power to the relay and relay socket, why the compressor will not run unless the trucks just been started.

I could use some help, its much appreciated,
Thanks,
Andy

 

Im not sure if its relevant, but the outside temp when I was doing all of this was 61, but in my other cars that have both manual, and eatc setups, the A/C will run even when its cold out.

 

There's always power to the relay socket when the ignition switch is in RUN. The PCM has to ground the "low" side of the coil in order for it to energize the relay. The PCM has to be happy with all its inputs before it will energize the relay.

Do you have a scan tool so that you can examine the various PIDs related to the HVAC system?

 

Just curious. Will the compressor run when you select the DEFROST mode on the EATC, and what is the LOW side pressure dropping to when the compressor is running?


-Mike

 

Sorry if i made my post confusing. I need to get a better scan tool so i can pull more pids. I have an old actron one that i use now, and i have one of the bluetooth units that i use sometimes but neither are up to snuff i dont think.
anyway, what i was trying to explain about the relay socket, is that i am able to pull the relay out, put my meter across the pins for the coil and see 12.5 volts. If i reverse the meter i see -12.5 volts so that seems to me that im getting a connection to both positive and negative, but even after seeing those values on my meter, it wont pull the relay in.

​​​​​​also, i have tried the defrost setting on the eatc, but to no avail, it does the same thing. Ill have to hook the gauges back up, but if i recall, the pressure on the low side would only drop to about 45 with the compressor running for ots 15 seconds.

please let me know if yall need any more info to aid in the troubleshooting.

​​​

 

I tried the defroster setting, and nothing changed. I also need to get a newer code scanner that will read more pids. I have an old actron scanner and a newer bluetooth unit but i need to see if itll pull more pids.

i need to clarify a bit. When i mentioned that i had battery voltage at the relay socket, i have 12 volts on the incoming terminal that sends power to the compressor when the relay closes, and i also have 12.5 volts when i hook my meter to the 85 and 86 terminals at the relay socket, which according to the schematic at the terminals that energize the coil inside the relay, and when i flip the test leads i get -12.5 volts so it looks to me like there is a ground present as well as 12.5 volts. I think its strange that the compressor runs for the 15 seconds when the truck is started, and that is telling me that the electrical side might be ok and that i might have an issue with the eatc. But i could be wrong.

what yall think.

 

You need to measure both sides of the coil relative to ground, one at a time, with the relay installed in order to get the true picture of what's going on.

Any scanner you get for this project needs to be able to access the UBP bus so it can also access the EATC module.

Have you run the EATC self-test to see if it has any DTCs?

 

If you have battery voltage at relay pin 85, the relay coil has power.
If you also have battery voltage at relay pin 86, that indicates that:
.....a) the relay coil has continuity through the coil, and
.....b) the relay coil circuit is not being pulled to ground (its not being turned on).

If the ground side pin was being pulled to ground, that pin would read less than battery voltage as it would be short the voltage being dropped across the relay's coil.

 

When i get home i will reinstall the relay and check both coil pins to ground and see what i get. I will also check both sides to ground as well. I.tried to pull any dtcs from the climate control unit, but couldnt remember the sequence for the newer style units, just the old. I hope if it has an issue it will have a code stored, but i may be out of luck as i had the battery disconnected to.do the tune up, so if im lucky, itll have one stored for me.

ill.let yall know what i find.

thanks guys

 

Well, i ran theneatc self test, and on the drivers side it said "24" and the passenger side said "77". I gotta look those up, but do those make any sense as relating to my issue.

 

Ok, with relay out...
pin 86 has 12v that switches on and off with the key, when positive lead from meter is on pin 86, and negative lead from meter is touching ground.
pin 85 has 12v when negative meter lead is connected to pin 85 and positive lead from meter is connected to battery. Voltage remains present until key is turned off, turning on the a/c or defrost from the eatc changes no readings.

 

You're supposed to do the readings with the relay IN, not out. Both with the negative meter lead to GROUND.

Why the heck did you make that reading, it doesn't follow the testing procedure recommended and, quite frankly, only confuses things.

 

Sorry im havin a brain fart
im supossed to test both sides of the relay coil with the negative meter lead on a ground correct

 

Yes, with the relay INSTALLED, engine running, AC set to ON but not working.

 

Ok, i tested both relay coil pins. Strangely enough, the compressor is now cycling on an off. It still runs for the 15 secs then shutd off like it originally did, but now it does it repeatedly which looks like a step in the right direction. It is 75 out today vs the 61 when i was working on it the other day. Dont know if that matters for anything besides system pressures but i figured id mention it.

Anyway, one coil pin was showing battery voltage constantly, and the other was showing battery voltage when the compressor was off and 0.22 when the compressor would cycle on. This is with the negative lead from the meter on a ground, and the positive lead being used to probe the relay pins.