Blend door actuator linkage

your on the right track! your blend door is broken or your blend door actuator is broken.

I believe your problem will either be a stuck or defective blend door panel, blend door actuator or restriction inside the heater core. An infrared laser thermometer is a great tool. If you can borrow or buy one please do so. To test the heater core you need to verify that the temperature going in and out of the heater core is similar and the temperature going into the heater core is similar to the engine temperature.

Right side or left ? Electronic Automatic Temperature Control or manual ? Temperature or mode door ?
Temperature Blend Door Actuator - LH Removal and Installation
NOTE: It is not required to install the new LH temperature blend door linkage parts included in the LH temperature blend door actuator service part kit if only the temperature blend door actuator requires replacement and the linkage parts are not broken or binding.
LH temperature blend door actuator and linkage

1. Remove the 2 lower steering column opening cover bolts.

1. Detach the lower steering column opening cover.

1. Disconnect the in-vehicle temperature sensor aspirator hose and electrical connector.

1. Position the instrument panel wire harness away from the LH temperature blend door actuator.

1. Remove the 3 LH temperature blend door actuator screws.

1. Disconnect the LH temperature blend door actuator electrical connector.

1. Remove the LH temperature blend door actuator.

1. Manually operate, and inspect the LH temperature blend door linkage for incorrect placement, binding or damage.

Temperature Blend Door Actuator - RH, Dual-Zone EATC Removal and Installation
NOTE: It is not required to install the new RH temperature blend door linkage parts included in the RH temperature blend door actuator service part kit if only the temperature blend door actuator requires replacement and the linkage parts are not broken or binding.
RH temperature blend door actuator and linkage

1. Disconnect the glove compartment damper from the glove compartment.

1. Remove the glove compartment.

1. Remove the RH lower instrument panel insulator.

1. Remove the RH lower floor console trim panel.

1. Remove the 3 RH temperature blend door actuator screws.

1. Disconnect the RH temperature blend door actuator electrical connector.

1. Remove the RH temperature blend door actuator.

1. Manually operate, and inspect the RH temperature blend door linkage for incorrect placement, binding or damage.
2. Mode Door Actuator - Defrost/Panel/Floor Door
3. Removal and Installation
   NOTE: The defrost/panel/floor mode door actuator can be accessed from below the driver side of the instrument panel.
   NOTE: It is not required to install the new defrost/panel/floor mode door linkage parts included in the defrost/panel/floor mode door actuator service part kit if only the mode door actuator requires replacement and the linkage parts are not broken or binding.
   Mode door actuator and linkage
   1. Remove the 3 defrost/panel/floor mode door actuator screws.
   1. Disconnect the defrost/panel/floor mode door actuator electrical connector.
   1. Remove the defrost/panel/floor mode door actuator.
   1. Manually operate, and inspect the defrost/panel/floor mode door linkage for incorrect placement or damage.
   Mode door actuator linkage only
   
   1. Remove the mode door linkage.
      1. Depress the tab and remove the panel door lever.
      1. Remove the floor/defrost door intermediate lever screw and floor/defrost door intermediate lever.
      1. Pull straight outward to remove the floor/defrost door lever.
   Mode door actuator and linkage
   
   1. NOTE: When installing the mode door actuator, make sure that the panel door lever and floor/defrost intermediate lever are correctly aligned with the mode door actuator cam.
      To install, reverse the removal procedure.

Bad blend door actuator is your cause. You need to disconnect the actuator from the blend door and manually check the blend door. One side of the door switches the heat and one draws air from the ac evaporator.

You have a problem wit the air temperature control blend or the blend door actuator motor, most times both are defective. The parts are located deep in the dash and as such the dash assembly must be removed to service the parts.

Possible bad blend door actuator .some gm cars can be relearned to the new climate control head

Air Temperature Control Blend Door Failure No Heat

In all modern cars there is a tiny DC electric motor driven gear drive that moves a plastic door that blends heated and cooled air from the AC and the heater core, this is called (interestedly enough) the air temperature control blend door actuator. The motor that moves this door fails because the door starts sticking from warping, most common complaint is no heat but it can be no AC as well. To replace these parts (blend door and blend door actuator) you must remove the entire dash from the car. Always have this problem confirmed by a dealer or qualified repair shop as it is a very expensive repair.

In all modern cars there is a tiny DC electric motor driven gear drive that moves a plastic door that blends heated and cooled air from the AC and the heater core, this is called (interestedly enough) the air temperature control blend door actuator. The motor that moves this door fails because the door starts sticking from warping, most common complaint is no heat but it can be no AC as well. To replace these parts (blend door and blend door actuator) you must remove the entire dash from the car.

your blend door motor or your blend door needs to be checked

the blend door actuator is bad. there about 70 dollars at ford. make sure you hook up the actuator and put the control on defrost before you bolt it on the air box or you will brake the blend door.