Cadillac: 1999 Eldorado HVAC Controls, candy apple red, diagnostic scanner

Question
Very recently my control panel stopped working properly. My dealer reports I need a control panel. His price is $1,200.00+ so I want to be sure there is no other way.

Symptoms are: Rear window heat inop but the fuse is OK; No control buttons result in action including front defrost; The indicators all seem willing to work; When I rotate the command temperature knob all the way to the left 60 degree stop, the fan runs on hi, the unit blows hard and cold, the leds go to show wher the are is comming from. Conversely, when I select full hot the results are hot and hard. When I select 68 degrees (oat 94) the unit blows softly and cools. It seems to be working in a lot of ways but definitely not in the way it has for the last 6 years. I have onlt 66,000 miles on this 275hp, candy apple red, dream car and and I would appreciat your favor of a reply. Thanks

Answer
I disagree with the dealers sstatement as being a faulty control panel, Unless they have already performed some diagnostics on the vehicle. In most cases the cause is the AC/Heater programmer (ACM).

Unfortunately the diagnostics requires the use of an expensive diagnostic scanner in order to make the diagnosis.

tom