My Explorer has full heat all the time. No control of air box damper using the heater control. I'm suspecting a loss of vacuum, bad vacuum switch or vacuum motor, etc. Before I dig in....does anybody have any suggestions for common causes of this problem?
By saying "no control of air box damper" do you mean that it won't switch between heat, defrost, vent, etc. or that you can't control the temperature?
Here's a follow-up to my own posting. By doing some more internet research, I found that this is a very common problem in '97-ish Explorers & Aerostar's, etc. The constant heat (or cold) is caused by a broken drive mechanism of the air mix damper door. I found a few websites that discuss this problem which indicate that the repair could cost upwards of $1000. However, a simple fix was outlined on several websites that show you how to do a modification to the damper door servo drive by drilling a hole and installing a drive pin (common 3 penny finish nail cut to size) on the servo shaft. I tried this today and it works fine. Time will tell.
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