Blend door actuator?

Hi,

You have a couple of things happening. First, the airflow direction is controlled by the engine vacuum. If it is stuck in defrost, that is the default position. When we need to do is remove the controller and disconnect the vacuum harness from the rear of it and confirm there is a vacuum to it with the engine running.

Next, the lack of heat can be caused by a plugged heater core or a blend air door not moving. On this truck, the blend air door is controlled by a cable and not vacuum. The only pic I could find to help was the lever on the HVAC box under the dash that the cable connects to. See pic 1. First, check to see if that lever moves when you change the controller temperature from cold to hot and back. If it doesn't, confirm the cable itself is moving. If it isn't, either the cable is broken or has come disconnected at the controller. You will see it when you remove it to check for a vacuum.

If the door does move, then I need you to do a simple test. Start the engine and turn the heater on high and allow the engine to reach operating temperature. Turn the engine off and feel both heater core hoses at the firewall where they attach to the heater core. Both should be hot. One will be slightly hotter than the other simply because one is a supply and the other is the return. Feel them to make sure they are hot.

Because of the model year, I have no directions showing how to remove the heater controller in the dash. But here is what to do:

Remove all the torx screws around the cluster holding the trim in place. If you have tilt wheel, put it in the lowest position and remove the cluster trim. Once that is off, you will see the controller is held in by two screws. Remove the screws and gently pull the controller out of the dash. It won't fully come out, but it will be enough to check the things I mentioned.

Let me know what you find or if you have questions.

Take care,

Joe

See pic below.