I have a 1997 F150 with a poltergeist or just a problem. The temperature contols on the AC and heater are not working as should. If on Max AC the air gets cold and then there is the thud of a door in the duct and I get MAX heat. Also, any change to warmer than max causes the temp to change to max heat. Further, there is no control of the heat when on heat. It is Max all the time. Even on vent it is max heat. The fan works fine and the heat goes off when you have the control in the off position. I have checked the climate control fuse and it was fine as expected. Is there a vacume relay or air mixing control somewhere. I have searched and can't find a control.

 

Check your switch. The actual AC and heater control switch. Also check that your blend door is opening and closing as it should.

 

Sounds like a blend door problem. Take the black cover off that is between the bottom of the dash and on top of the tranny hump. Watch under the dash in that area and you should be able to see the actuator work when you turn the system on. The problem is that the door breaks were the actuator attaches to it or on the hinge. I would replace the actuator motor too!

 

I am having the same problem. But I don’t see or hear anything happening in this area. I am a bit of a newbee trying to save a few bucks. I have a 2000 f150 I don’t think there is too much difference. I have uploaded a pic of the bottom of my dash . Not quite sure what to look for. Sorry for being a rookie just would like to learn. I Love my truck and would sell my wife first LOL!
Any help would be appreciated

 

I had this problem in my 97 Ranger. The blend doors in the Ranger are electric. The top of the blend door stripped out. I took the motor off and put a piece of vac line on the stub sticking up and added a lil bit of gorilla glue and re-set the motor on top. That fixed it till I sold it a year later. Thats the cheap and easy way. The correct way is pull the box out from the dash and replace the blend door or motor.

 

New here, first post

I know this is a old thred But I dont see any definet answers

How does this black cover come off, above the transmition hump?

Does the blend door operate on vacume only? How much vacume does it need?