I am having issues with my heat in my cab. I have a 2004 f150 xlt and my truck gets up to temp, but no heat blows out of vents. I replaced my thermostat thinking that was the problem, but nope. Most of the time after anywhere from 2 mins to 10 mins, the heat will start. If I move the dial to cold then back to warm, once again it takes some time for the heat to return. What could it be?

Thanks

 

Plugged heater core?

Automatic or manual temperature control?

 

Maybe? once I get heat, I'm good to go unless I switch the dial to cold and back to hot, I got nothing for a while?

Manual

 

Your description sounds a lot like your Heater Blend Door Actuator has failed. To check, you'll need to take out your radio to gain access to the top of the heater core box. Then remove the three screws that hold the Heater Blend Door Actuator to the top of the heater core box. Leave the wiring harness connected for the test. (Removing the Blend Door Actuator isn't difficult, but there are several YouTube videos that will lead you through this process if you need a visual.)

After removing the Blend Door Actuator from the heater core box (wiring harness still attached), place your ignition in the Key On Engine Off position. Slowly turn the temperature dial on your HVAC controls back and forth between full hot and full cold. If the blend door actuator stops working or works only intermittently during this test, then it should be replaced. The part is about $30 at your local auto parts store, can be cheaper if purchased online.

Of course, the problem could be a stuck/sticking blend door (a much more complicated fix) or a plugged heater core as glc mentioned. However, it's fairly easy to check the blend door actuator, and this is a relatively common failure on an F-150 that is more than 10 years old.

I hope this helps!

Updated to add: if air is coming out of your vents but it's the wrong temp, then the blend door actuator could be the problem. If you're not getting any air at all regardless of selected temp, then the problem is something else.

 

Just a little update. I replaced the bled door actuator and that wasn't it. Once it get heat coming out of the vents, I switched it to cold, and heat continued to come out for maybe a min or 2, then switched to cold. I switched it back to hot, a min later hot air started blowing??

my hvac control seems to be moving kind of freely? could that maybe be the issue, the dial is broken so its not reading what temp it should be at?

 

Well, its been close to a year now, and im still having problems. My AC stopped working this summer (about 2 months ago) so I thought it was low on coolant. I checked it and it was slightly low, but within tolerance. Everything seems to be working, but it just blows warm air. Also, when I change from defrost to vents (or any change for that matter) it takes a while to change, or sometimes I have to shut it off to get it to change. So which brings me back to my HVAC controls are possibly bad? maybe its not correctly selecting the correct temp? IDK, not sure what else to do?