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I've had this problem for some time now. The climate control portion of my IPC displays "--" on the outside temp and temp setting. When I first had this problem it would only stay like this for a few minutes and then display the numbers. Now it stays like this all the time and since it's starting to get warm out I would like to fix it. I've also noticed that when it shows "--" the cruise control does not work. I was looking in the Haynes manual I have for how these systems relate but the Haynes manual isn't the most informative by any means.

Thanks for the help

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Make sure the temperature sensor located behind the grille is making good contact with the harness that plugs into it. My Seville loves to play weird electrical games like this every spring and affects mostly the blower motor for me. I think it has something to do with the rubber seals on the harness' that are expanding now and may be actually pushing the contacts away from each other ever so slightly to break contact.

As for the cruise control... When you engage cruise does the IPC display "CRUISE ENGAGED"?

If so, then it is very likely that it is just a vacuum line that may be disconnected (most often that it is off the cruise servo itself).

I cannot see any way that these two problems are related, unless you are having a electrical malfunction within the cars electrical system itself which could be anything from the BCM or PCM to even a short or faulty ground somewhere.

As always, pull the codes (if any) and then start from there.

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When I get off work I'll check that sensor. I remember when I got the car that sensor was just hanging down in front of the AC condenser so I reattached it.

I don't think that the IPC has ever said "CRUISE ENGAGED" or anything to let me know the cruise is on. The cruise control does work though when the climate control display is functioning properly. When I was coming to work this morning the display started to show numbers so I engaged the cruise and it worked for maybe a minute before it disengaged and I noticed the display was showing "--" again.

If it were a ground where should I look. I was thinking maybe on the IPC itself but I'd like to get someone else's opinion before I remove it.

Anyways, I'll check the connection and codes in a few and let you know what I find.

Thanks

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I am not sure as to what particular electronic system address' the cruise control. I would like to think the BCM but am really not sure with your year. I guess we know they both work, but with the symptoms you seem to be having it does seem like something could be loose.

If the sensor was dangling at one point then be sure to check the harness plug for breaks or cracks as it may have been damaged, but I still cannot see how that would be the issue as it seems the problem comes before the temp sensor and cruise.

Perhaps others will chime in on this.

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The DTCs I got were:

IO37 Current

IO39 History

I've also noticed that this problem happens more when it's warm out. Last night it was about 60 degrees out and I had no problems with it. It's typically been around 80 degrees and it never seems to work at these temps.

Thanks for the help.

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Now I'm thinking the outside temperature doesn't make a difference on the way this operates. I think it's probably just a bad connection somewhere. Would the sensor behind the grille cause this if it were faulty.

Thanks

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The DTCs I got were:

IO37 Current

IO39 History

I've also noticed that this problem happens more when it's warm out. Last night it was about 60 degrees out and I had no problems with it. It's typically been around 80 degrees and it never seems to work at these temps.

Thanks for the help.

I037 ...................................... Loss of Air Conditioning Programmer Data

This current code is the cause of your problem, Ill look in my 91 manual and see if I can find any helpful info

Pre-1995 - DTC codes OBD1  >>

1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm

How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/

Cadillac History & Specifications Year by Year  http://www.motorera.com/cadillac/index.htm

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I037 ...................................... Loss of Air Conditioning Programmer Data

This current code is the cause of your problem, Ill look in my 91 manual and see if I can find any helpful info

I don't think that my refrigerant is charged. Could this cause the problem?

I also remembered that when I had removed the PCM that the heater/AC box was missing some screws and there was a module that wasn't attached like it should have been. Could this be a problem? I replaced the missing screws and reattached the module.

Anyways, I just thought I'd throw this out there in case it might help the diagnosis.

Thanks

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I can't see how the sensor behind the grille could cause this problem.

Perhaps when the car warms up this problem occurs?

A fair amount of heat is produced inside the dash from lights and electronics and even when using the heater and perhaps when things warm up a bit a connection is being affected...

Just a possibility.

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I can't see how the sensor behind the grille could cause this problem.

Perhaps when the car warms up this problem occurs?

A fair amount of heat is produced inside the dash from lights and electronics and even when using the heater and perhaps when things warm up a bit a connection is being affected...

Just a possibility.

I don't think it's the sensor anymore myself. I'm pretty sure it's a connection. Should I check connections on the IPC or should I look elsewhere?

Thanks

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Go to a parts store and see if you can find a can of electrical contact cleaner and dielectric grease.

Then I would disconnect the negative battery terminal and start tearing into your dash little by little.

If you have a factory service manual then you can probably get this done in a couple of hours; but I would start with the IPC, then move on to the ECM, BCM, etc.

Check each connection to see if all the contacts are making good contact and clean any corroded or dirty ones with the cleaner. Make sure to apply the grease afterward to make better contact and to prevent future oxidation of the contacts. My only fear here is that one of the modules could just be faulty and all the checking, cleaning and greasing could be wasted time... Maybe someone else will chime in who might know how to test the modules...

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  • 5 months later...

I know this is quite belated but I thought it might help others. I fixed my climate control problem recently. It was a problem with the fuses under the hood. The BLWR FDBK and A/C COMP fuses were both loose in their connectors. The connectors were really stretched out for some reason so I squeezed them back together and problem solved. I wish I would've figured this out over the summer though but now is better than never. Anyways, I hope this helps.

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