Heater temp control works only in position it is placed when truck is started,as soon as you accelerate the a/c mode kicks out and goes to heat. Just what you want when it is 90 degrees outside. Heat fubction only works if started in the floor position with temp control on hot. Vacuum problem ???? Where to start?

SOURCE: HEATER TEMP CONTROL IS STUCK ON HEAT. WILL NOT SWITCH TO COOL

sounds like your blend door actuator has failed, or the lost vacuum to this actuator, or something got into the vents holding the blend door into position. Most common is the acuator failing, good news is its a fairly inexpensive part, but gettin to it is not fun, its it the ductwork in behind the dash, I'm not sure on your specific model but most I have seen the dash has to come completely out. If it gets to that point you may want a repair shop to do that.But hopefully you get lucky and its easy access.

SOURCE: No dashboard heat output

The climate control was poorly designed on these cars.

There is only heat on the floor and defrost settings, due to the layout of the ductwork.

Marvin

• 85242 Answers
• Posted on Feb 21, 2009

SOURCE: 1997 F150 heater problem

your problem is caused by the air temperature control blend door actuator motor being defective, the little motor moves the door that gives either hot air or cold air or a blend of the 2.

SOURCE: ford ka heater blows hot air all the time

Your problem is a faulty heater control valve. The design used on these vehicles allows for hot water to flow constantly and compete with the evaporator as there is no blender door. You have to replace the valve and possibly the control head. Meanwhile, you can bypass the valve to have cold air

Dana Newcombe

• 1564 Answers
• Posted on Jan 20, 2010

SOURCE: 1997 ford e250 van. heat only no cool air.

One of your deflector door servos or the door itself, is hanging up. To determine this more clearly, run your vehicle for about two minutes and shut down the engine. Move your function selector knob from defrost to floor to panel and listen carefully for a sweeeping sound. if you do not hear this sound you've got to check under the dash for a loose vacuum line or under the hood for a loose or broken line to the vacuum accumulator. The vacuum accumulator is a large black ball on the firewall with only two lines connected to it. One line is about3/32nds of an inch and the other will be about one quarter inch. Check these lines well, for they control ALL the functions within yout climate control. Best of luck my friend, Dana