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Discussion Starter #1
Hello all,

I have a 88 DeVille which has develop this issue:
Start engine, tehn pressing "Auto" climate control, with-in 1/2 sec it switches to "Econ", cannot get heat or air out of the system.
Have read through many posts and fully understand that under Econ the AC will not be running.
Can a kind soul please help me with this? believe I have several problems, but cannot determine which is first.

Thanks for your help,

Adriano:tisk:
 

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Usually, that is a sign of low A/C pressures. You most likely need the A/C serviced. Does it work ok in ECON mode?
 

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Discussion Starter #3
Hello and thanks for your reply,

No Nothing appears to work on either auto or econ, just the information in the control center (lights, indicators, etc..). Any ideas?

Thanks
 

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Discussion Starter #6
Thanks guy's,

Really weird,
I can raise the temp readings by pressing the up/dn buttons, but NO heat out of the ducts at eception at/during idle condition. NO I cannot hear the fan run or feel/hear any attempts for the blower to start.

Any further suggestions would be greatly apreciated.

Adriano
 

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Sounds like a dead blower motor or control module. I think there may be a module on top of the HVAC box on the firewall.
 

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You don't mention a "Service Air Conditioning" message. You should see this message for two seconds when you turn the key ON, and after every cranking cycle. You should also see the message for 30 seconds every time you press AUTO with an AC fault present. Are you getting one? If not, the bulb may be bad or missing. Also check fuses. If the fuses and bulb are good, and you never see the "Service Air Conditioning" message, I suspect the BCM is defective.

If you are getting a service tattletale, pull the codes by pressing OFF and WARMER (Key on) until the displays begin to cycle. The fuel data center on the left will have a series of codes. "..E" are stored ECM faults. ".E.E" are current ECM detected faults. "..F" are faults stored in BCM memory. ".F.F" are current BCM detected faults. ".7.0" is the end of the cycle and the computers are waiting for further commands. You can clear codes from ECM memory by pressing OFF and HI. Clear BCM codes by pressing OFF and LO. Pressing AUTO exits the diagnostic mode. Write down all codes and then search the forums for an explanation of each.
 

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Its an 88, theres no scrolling message to read every 30 seconds.

But more than likely, its the control on the air duct under the hood up by the wipers. This part went out on my 86 and my 91. Not sure how a heat sink can quit, but they do and new price was $175, bone yard for the 91 cost me $15.
 

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Discussion Starter #10
Hello Cl1986, thanks for your reply. The placement of the control module you said is in the engenine compartment somewhere around the wiper part? Got to pulling wires and checking fuses last night and was able to get the fan blowing again, but after a few seconds of warm air output and changing the temp down and back up only cold output.
Will check my area bone yards to see what I can pull $175 is quite steep.
Thanks
 

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If you got the fan going, forget the boneyard. The control module is fine. Just clean the connections. Try flushing your heater core.
 

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cl1986 said:
Its an 88, theres no scrolling message to read every 30 seconds.
The '88 Deville does have a "Service Air Conditioner" tattletale. It doesn't scroll, it lights up. It comes on for 30 seconds every time you press AUTO if there is a fault (low refrigerant) in the AC. The BCM checks the temperature differential between the high side and low side. It also checks the A/C Low Pressure switch and will light the tattletale if the pressure falls below 8 psi.

I am glad you got the blower working.
 

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Discussion Starter #14
Hello all,

thanks for all teh helpful hints.
Did get under the hood last week originally to locate the control module, but then I started looking around for other possibilities. Found my stupidity under there, at some point and time I must've moved the core rubber hose to get to some other parts and forget to unkink it back....that was most of my problem. Now I have heat but only while rolling, at stand still idle, not much, must've damaged the hose. will get another and replace.

Adriano
 
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