Hey everyone, having an issue with my heat. heater core is good, system has been flushed. I get about 10 seconds of heat, then it blows cold. I have a 2001 f150 with a 5.4. I have the analog or dial temperature control unit. I also only have high speed setting. been told possibly blend door but I get a little heat then it goes away. could it possibly be the temperature control unit? I am perplexed by this. also have an engine sputter around 50mph. Almost seems it happens when I am just cruising, but if I am in the throttle it doesn't happen. any help would be greatly appreciated. thanks in advance

 

Replace your blower motor actuator, that will fix your high speed only. There are two different ones so pull your old one and take it with you to parts store. Your sputter could be time for a tune up.

 

JS is right on with the one speed blower.

Are both of your heater hoses going to your firewall warm after the engine has warmed up? If they are then your blend door is doing something screwy. May be a vacuum line problem.

You have a low grade misfire. If you have a CEL get the codes read. If not then get a tuner that can read live data or download the torque app. to help identify what cylinder is misfiring.

 

Thank you for the help. Blend door appears to be good. Blend door resistor is good. Blend door motor struggles when moving hot to cold and also shutters back and forth without even moving the thermostat. Could that be an issue with the motor? Or perhaps an issue with the control unit on the dash? Changed the plugs a few months back, they still looked pretty good but changed anyway given the pain it was to get them. Thinking possible coil pack going out

 

I'm leaning toward a coil as well. That blend door shouldn't be moving like that. It should be steady until you tell it to move. I would suspect the motor or another mechanical part has play in it somewhere.

 

If your blend door struggles to open the gear is probably broken. Should open and close smoothly. You can try replacing your blend door motor but probably gonna need a new blend door.