I have a 2001 eldorado esc. 141,000 miles. One of my sides the passenger side the heat will not blow warm air, it is as if one side of the vents, drivers side has warm air and the other blows air from the outside without being heated. Please help.

 

'Sounds like the vacuum that opens and closes the vents is not operating properly or one of the vents is stuck. If one duct is blowing warmer air it may be stuck open to draw heat off the engine or outside air that is much warmer than the A/C air. Note the function that you have selected (ie. A/C or economy/outside air vent openned or heat), then observe which duct is conducting the appropriate air temperature. You may have to select extremes in order to accurately tell the difference between the air current temperatures. If you select cold but get warm out of an isolated duct you may have narrowed your search to a faulty vacuum seal or a sticky vent at that point. As you are messing around with your controls and switching between heat and A/C you may hear the slight sipping noise of ducts closing against the vacuum or you may hear some other anomaly that gives you the clue that something is mechanically hung up inside.

What does this all do for you? Well, if you don't tear into the dash yourself (I wouldn't simply because I hate working on cars) you at least have a better description of what is going on for your interview with the mechanic. The more detail about the symptoms you give him will either expose his ineptitude or his genius. I have found that a plethora of detail will often snow the mechanic into thinking that I really know what the problem is and that I am testing him to see how fast he comes up with the correct diagnosis. A few extra pens and a tire gauge in your shirt pocket may help this act. If he comes up with the answer too fast and tries to sell you a new heating sytem or A/C unit, look him straight in the eye and don't say a thing. The defiant silence will usually bring out the truth in the phrase, "Well, it might only be..."