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HELP! A/C cold at idle, warm at highway speed

04-28-2009, 04:40 PM
I need some advice on my son's 98 Eldorado A/C system, I just got it out of two shops, one a local yokel another a Houston Cadillac dealer, both appear clueless on this problem. The local yokels put freon in and said it was good. The Cad dealer put an door actuator on the vent system. The car has ice cold air at idle and speed up to about 20 mph, or when the engine is 1000 rpm or less. At higher speed, the A/C warms up about 15 degrees, the Cad guys thought one of the doors in the hvac system was not closing apparently, whatever, neither guy has fixed yet and I'm down $700, although I will not quit with the Cad dealer who's into me for $450 and was the last to work on it. Any ideas are greatly appreciated.

FYI the compressor is apparently ok and is not shutting off during drive to cause the warming and there is plenty of freon, as seen by the cold air at idle.


04-29-2009, 08:08 AM
The question here is, is the auto hvac modulating the temps electronically or is the a/c system itself not producing cold air, no quick answer with this.

05-26-2009, 04:57 PM
idk i'd check the HVAC cover. it's a black plastic POS cover behind the valve cover next to the blower motor. they crack and break apart leaving holes to those doors that the dealer replaced. oh, and can be fixed with duct tape :)
not a guarantee but the symptoms fit and man it'd be nice to save another 700 :o

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