Hello, my wife and I own a 98 f 150 XL extended cab 4x4. It has air conditioning and recently we lost the ability to adjust the temperature on the heater, It has been blowing hot air no matter where we set the dial. My wife took it in to our local ford dealer and the service manager told her it might cost up to $1500.00 just to find out what is wrong. Anybody got any ideas?

 

first check the **** on the temp control. these tend to crack along the flat side and then it doesn't turn the shaft. it just pulls off. try turning just the shaft. hopefully this is your problem. a $6 part.
if not it may be the blend door. if you search blend door you will see how to fix or replace it.

 

Even if it is not one of the two things lees99f150 suggested (and it probably is one of those) you do not have to go to the dealer for A/C work. Any local A/C shop will probably be a LOT cheaper, faster and probably better.
A/C shops make their living on doing A/C correctly. Dealerships make their living on selling you a new truck...

Also, a service tip that I hate to have to give. Go into the place yourself. Men tend to get much lower estimates than women from the same place.

All us old married guys tend to send our wives in for stuff like that, but most of us have learned the hard way that estimates/prices go up a LOT on technical stuff when a woman asks.
Sad but true.
Chris