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Question -
I have a 1998 Lincoln Mark V111 .The heat & Ac is not working properly .I have a electronic control system there is always hot air coming out even when I put the AC on or lower the temperature down to 60 degrees.I replaced the A/C-heater control module with a used one & still have the same problem.
Thanks Al
Answer -
You have a 50/50 chance of this USED part as being GOOD. This particular part has a high failure rate and unless you TEST the component to see IF it is OK, You could very likely have a faulty one.
Just in front of the heater core there is what is called a DAMPER DOOR that is opened and closed via the A/C-Heater CONTROLLER via a metal arm that you can physically see moving back and forth as you increase and decrease the temperature setting via the control panel. look to see IF this metal arm is moving.
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I checked the arm that opens & closes the damper door as you said, and it does not move.I can move it manually then I get cold air then move it back & get hot air.Does that mean a bad a/c-heater control module .How much do you think a new one costs. The used one costs $125.
Thanks Al
AnswerIF you have proper air delivery coming out of the center air ducts on the dash as well as air flow to your feet and to the defroster this is VITAL. If you do NOT have proper air flow from these vents and ONLY have air flow from the defroster vent this would be a classic loss of vacuum to the main controller under the dash usually located behind the glove box. Make SURE that you have engine vacuum to the BLACK vacuum hose that goes into this controller. If you DO have vacuum at the black plastic line, this would in most cases be an internal failure of the controller and is NOT operating the damper dor controller.
However, You MUST test the controller inputs BEFORE you replace it. Also the damper door control rod that comes out of the controller MUST be properly adjusted at the damper door handle.
A NEW controller usually runs about $150-$200.00
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