03 explorer ac control module

[Dino360]

My 04 Eddie Bauer has a jumper wire that bypasses normal ac operation by tapping into the relay in the relay box under the hood to hot wire the compressor. My climate control panel on the dash was displaying ext temp of 107° all the time so I replaced it with another one and now seems to be displaying the correct temperature.

The issue I was having is that the ac compressor being wired that way makes it run constantly whenever the truck is running. I am not able to shut it off by selecting off on the control panel and since it's running all the time, it freezes up the evaporator after about 45 minutes of driving.

My scan tool only reads the signal for the external temp sensor and not the test of the ac system. I took it to a mechanic that has a better scan tool and he tells me they're getting a failed to communicate error when trying to read the ac codes and that they are getting a code for the ac control module. They're telling me that the control unit needs to be programed to the truck. Does this sound right to anyone? If so is that something a dealer needs to do?



Thanks for any help

 

[J_C]

I don't understand your issue. I mean you state it has a jumper wire causing it to stay permanently on, so why not just remove that jumper wire?

No it does not sound right that the control unit would need programmed to the vehicle. It's possible that your system has not changed much (if at all) compared to a 2nd gen Explorer with EATC so I've attached the workshop manual pages for that.

 

[Dino360]

Thanks for the reply. With the jumper disconnected the compressor will not engage. I drive it till the air at the vents have little to no airflow then unplug the jumper so the evaporator can defrost. As stated I replaced the control unit on the dash. I read that some vehicles use ambient temperature sensors inside and out to control the ac compressor. I replaced the sensor up by the grill and my scanner said the outside temperature was reading 82 (which was accurate) but the display inside was stuck at 107. After replacing the unit it was reading correctly for a day or so, Now reading 50° when it's actually 94 outside. I'm not sure how much ambient temperature sensors affect it but I'm including it to give a much information as possible. I've never heard of having to have the control unit programed to the vehicle so that didn't sound right to me either. I'll read the material you sent and see if I can make sense of it.

Thank you

 

[J_C]

Seems odd that it worked for a day then stopped. I'd wonder if the wire to the sensor is damaged or corroded connector. Unfortunately I don't know what the resistance value vs temperature should be but if you can find that out then you can measure for it on the head unit connector. Something like that might be mentioned in the PDF I attached in the last post.

 

[Dino360]

I ran the EATC self tests by holding down the Off and defrost down then hitting the auto button. It started to display 2166, 2167,1255, and 1251 then repeated itself. Once I did this I selected the defrost which cleared those codes and got the display to reflect accurate ext temperature. . Now if I run the self test the whole control cluster lights up and displays 88.8-188 as shown in the picture which I believe means no codes were found. I did disconnect the jumper to see if reseting helped but it did not. Do you know if there is an internal car temp sensor that I can replace? The 1251 and 1255 code are ambient sensor codes but I'm not sure how to locate the interior temp sensor.

 

[J_C]

I don't know their location, seems to be an interior sensor, maybe on a white piece of corrogated hose that you might see with glovebox removed, (example: FORD EXPLORER MERC MOUNTAINEER EATC INTERIOR INSIDE CABIN AIR TEMP SENSOR W HOSE | eBay ) and a sunlight load sensor, that's "maybe" the one on the windshield mirror? I don't know, would also look at the dash for a bump sticking up to be the sunlight sensor, or from the outside of the base of the windshield looking in and using a strong flashlight.

Edit: That ebay listing I linked above has ended so it is convoluted to see the picture of it so I've reposted it here:

Is there the possibility that the sensor was not plugged in, in the first place so when you went to replace it, it still didn't get connected? I would pull the radio and look around behind it to see if there are any stray connectors or connector locations unused on the EATC console/head unit.

I don't know if the following diagram is right for your model year but through wire colors or possibly process of elimination could ID the wires and trace them...

Sun load sensor

Waas just looking at the wiring diagram on my 99 Mounty and noticed a sun load sensor....anyone have any clue?

www.explorerforum.com

Interior Temperature Sensor - Ford Truck Enthusiasts Forums

1997-2006 Expedition & Navigator - Interior Temperature Sensor - Two weeks ago me and my dad undertook the tedious job of replacing my heater core (and yes, 14 hours later, we completely wish we had just taken it in and paid the $600). Everything went relatively smooth, time-consuming with some...

www.ford-trucks.com

 

[Dino360]

I don't know their location, seems to be an interior sensor, maybe on a white piece of corrogated hose that you might see with glovebox removed, (example: FORD EXPLORER MERC MOUNTAINEER EATC INTERIOR INSIDE CABIN AIR TEMP SENSOR W HOSE | eBay ) and a sunlight load sensor, that's "maybe" the one on the windshield mirror? I don't know, would also look at the dash for a bump sticking up to be the sunlight sensor, or from the outside of the base of the windshield looking in and using a strong flashlight.

Is there the possibility that the sensor was not plugged in, in the first place so when you went to replace it, it still didn't get connected? I would pull the radio and look around behind it to see if there are any stray connectors or connector locations unused on the EATC console/head unit.

I don't know if the following diagram is right for your model year but through wire colors or possibly process of elimination could ID the wires and trace them...

Sun load sensor

Waas just looking at the wiring diagram on my 99 Mounty and noticed a sun load sensor....anyone have any clue?

www.explorerforum.com

View attachment 331863

Interior Temperature Sensor - Ford Truck Enthusiasts Forums

1997-2006 Expedition & Navigator - Interior Temperature Sensor - Two weeks ago me and my dad undertook the tedious job of replacing my heater core (and yes, 14 hours later, we completely wish we had just taken it in and paid the $600). Everything went relatively smooth, time-consuming with some...

www.ford-trucks.com

 

[Dino360]

Anything is totally possible. I bought the truck like this 2 years ago from some guys from Mexico, no telling what they're capable of after seeing the hack job they had under the hood. Those guys are known for doing half ass **** like that. I've already untangled most of the mess they created but this one is still causing issues. I'm thinking it might be here on the dash to the right of the steering column. If it's there I'm gonna put an ohm meter on it and use a heat gun to see if it's functioning.

 

[Dino360]

Anything is totally possible. I bought the truck like this 2 years ago from some guys from Mexico, no telling what they're capable of after seeing the hack job they had under the hood. Those guys are known for doing half ass **** like that. I've already untangled most of the mess they created but this one is still causing issues. I'm thinking it might be here on the dash to the right of the steering column. If it's there I'm gonna put an ohm meter on it and use a heat gun to see if it's functioning.

View attachment 331865

 

[Dino360]

I found this behind that small vent. The little resistor faces toward the driver and the round end fits in a white plastic tube that runs into the dash, presumably to the eatc. I'm gonna try to test it but I'm not sure what the parameters should be. Is also pretty dirty so I'm thinking of cleaning it maybe with mass airflow sensor cleaner? I'm not sure how sensitive it is.

 

[Dino360]

I found this behind that small vent. The little resistor faces toward the driver and the round end fits in a white plastic tube that runs into the dash, presumably to the eatc. I'm gonna try to test it but I'm not sure what the parameters should be. Is also pretty dirty so I'm thinking of cleaning it maybe with mass airflow sensor cleaner? I'm not sure how sensitive it is.

View attachment 331868

View attachment 331869

I tested it at about 25.5 k ohms and it dropped into the teens when I applied warm air. It returned back to mid twenties after I stopped. It definitely reacts to heat but I'm not sure if 25 k ohms is within normal parameters.

 

[J_C]

I wouldn't bother cleaning it until you see if it's roughly correct, I mean that little bit of gunk won't make much difference on something like this, compared to a MAF sensor anyway, but now I see you posted that you tested it and it seems to respond so sure, I'd clean it off with MAF cleaner or even rubbing alcohol and a cotton swab - it is not as delicate as the MAF.

See that PDF I attached previously, that is my only source of info on page 29 where it reads:

Is the resistance within the specified values for these temperature ranges: 10-20°C (50-68°F) 37,000-58,000 ohms, 20-30°C (68-86°F) 24,000-37,000 ohms, 30-40°C (86-104°F) 16,000-24,000 ohms?​

Yes GO to B12512​ (which is the next step on that PDF page 29).

My 2nd gen Explorer doesn't have EATC and I'm at the limit of what I know about the sensors besides following that Workshop Manual PDF. Odds are it is going to be the same for your '04 or at least close enough to test a lot.

https://www.explorerforum.com/forums/attachments/air-conditioning-412-00-climate-control-1999-workshop-manual-pdf.331790/