Hello, im new to this forum and need some help. I have a 1997 F150 4.6 V8 with a strange heater issue. When you first start it up from sitting all nite long you can turn heat on and just blows cold air, but it you turn temp control **** from hot to cold a few times all of the sudden the air is hot but you can turn control back to cold and still blows hot. it does not matter if you have the air coming from defrost, vents or floor it just blows hot until you let it sit again over nite. any ideas.

Thanks

 

My 99 was doing stuff like that, I took the control out, and sprayed the connections on the back with electrical contact cleaner and it works right now.

 

Thanks, i will try that in a few mins

 

That did not work.

 

Sounds like the blend door motor is bad . It will bind and shut down . It goes through a homing process at key on . It can work then not .

 

Now , you want to know where it is ?

 

Im afraid to ask : ) but tell me any way

 

Not too bad to see . A bit harder to unbolt . Directly under the radio , at the floor . Take off the trim panel , you will see the plug . Take off a few bits , ducts , a few bolts . It will be in your hand . Tight though . You can test it , with a DMM and a wiring diagram , and a few jumpers . They have a small motor and plastic gears inside . The gears usually break , or the motors rust . Worst case , a broken blend door . YOU DON"T want that . 8 hour job . But I got a few tricks , down to 4 .

 

I had a similar problem with my 99, replaced the temperature controller and it works fine now. I could rotate my temperature switch back and forth several times and it would eventually start working. Found the part on ebay vs. going to a dealer. You may also want to check your ****. I've had it crack on two different Ford's. Try swapping ***** to determine if that may be the problem.

 

Update:

First of all, i want to thank everyone for the imput that you have given me. This forum is great. After checking everything i could check i decided to drop glove box and cut the plastic out and cut a hole in the box big enough to stick my hand into it. What i found was the blend door would move freely with no resistance at all.

 

I suspect I may have the same problem. Have you fixed yours yet and if so, how much did it cost and how long did it take?

 

Sounds like he has a broken blend door , Not cheep to fix .DIY , Not so bad .I would still hope for a bad blend motor .I have a few tricks , don't have to discharge the air . Dash has to come out to fix blend door or heater core .But motor is fairly easy to replace . As stated above , ***** crack often . But controllers on these are less likely to fail , but can .

 

I have not fix it yet. My truck has 220,00 miles on it. i only dove it about 5,000 miles total in 2012. The truck still rides and drives great. i will just close blend door for AC and open it when i need heat. I just dont want to put a whole lot money into the truck.
i have owned the truck since 2002 and the truck had 97,000 miles on it when i bought it. But still looks pretty good and still in style. : )

 

Thanks for the update . If you do fix it , let us know . Good Luck !