Can Raise Temp Setting, But It Will Not Go Lower. WHY? I just purchased a used 2006 Mercury Montego. I have read a lot about "heater blend door" problems and EATC diagnostics, but nowhere have I read the exact symptoms that I am experiencing. When I turned the EATC on the temperature settings for both driver and passenger were set at 75F.
Then I can turn on the A/C but the temperature setting buttons to decrease the driver or passenger temperature will not go below 75F. If I raise the temperature the display increases properly, but then it will not go below this newer setting. Right now my settings are 80F-driver and 90F-passenger and they will not decrease. Possible cause: Went to start the car last night and it wouldn't start. The battery cable was extremely loose.
Took the cable completely off, cleaned it and replaced/tightened. Car started. But electronic displays for trip counters, etc. Were reset. Noticed that the temperature settings in the EATC were both back to 75F. However, same problem. Can only increase the display settings, never will it go below the setting displayed.
Wednesday, March 7th, 2012 AT 2:09 PM