Heater blend door is stuck

This van uses a power operated air temperature control blend door inside the air ducting, if the electric actuator that moves the door is defective or the door gets stuck (both are common) then you either get stuck with hot air or cold air all the time, that is likely your problem. To replace the blend door requires the venture dash be removed. Please have this confirmed by the dealer before you remove the dash which is a 12-14 hour job for an amateur

first, check under te hood to see if the heater core water hoses are hot going in and coming out. If hot going in but cold coming out, water valve (if you have one) may not be working.
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Control System Outputs
The air management doors are controlled by vacuum control motors (18A318) and an A/C electronic door actuator motor (19E616). The air inlet and distribution doors are controlled by vacuum control motors. The temperature blend door is controlled by the A/C electronic door actuator motor.
The A/C electronic door actuator motor provides a variable number of temperature blend door positions. Temperature control position energizes the A/C electronic door actuator motor moving the temperature blend door.
Vacuum control motors are used on both air distribution and air inlet doors. The air inlet and panel/defrost doors use a two position vacuum control motor. The floor duct/panel door uses a three position vacuum control motor. Vacuum control motors are controlled by engine vacuum through the climate control head.
For more information on the control components Section 412-04 .
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Air Management Doors
The air management doors are controlled by vacuum control motors (18A318) and an A/C electronic door actuator motor (19E616). The air inlet and distribution doors are controlled by a vacuum control motor. The temperature blend door is controlled by the A/C electronic door actuator motor.
The A/C electronic door actuator motor provides a variable number of temperature blend door positions. Temperature control position energizes the A/C electronic door actuator motor moving the temperature blend door.
Vacuum control motors are used on both air distribution and air inlet doors. The air inlet and panel/defrost doors use a two position vacuum control motor. The floor duct/panel door uses a three position vacuum control motor. Vacuum control motors are controlled by engine vacuum through the climate control head.
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Section 412-04: Control Components - Climate Control 1997 F-150, F-250 Workshop Manual
REMOVAL AND INSTALLATION A/C Electronic Actuator
Removal

1. Remove the floor duct panel.
   • Remove the two plastic push pins (one each side) and release the expander clip.

1. Remove the RH instrument panel brace.
   1. Remove the lower nut.
   1. Remove the upper bolt.
   1. Remove the brace.

1. Remove the LH instrument panel lower nut and position brace out of the way.

1. Disconnect the vacuum harness from the vacuum actuator.

1. Remove the floor duct.
   1. Remove the two screws (one each side).
   1. Remove the floor duct.

1. Remove the panel/floor door vacuum control motor.
   1. Disconnect the vacuum line connector.
   1. Remove the two panel/floor door vacuum control motor screws.
   1. Slide the rod out of the door and remove the panel/floor door vacuum control motor.

1. Remove the electronic actuator.
   1. Disconnect the electrical connector.
   1. Remove the three screws.
   1. Pull down to release the actuator shaft and remove the electronic actuator.

Here are the instructions with a diagram. If you need to enlarge the diagram save it to your picture files and then enlarge it there.

1. Disconnect battery ground cable, then drain cooling system. See: Engine, Cooling and Exhaust\Cooling System\Service and Repair

2. Disconnect heater hoses from heater core. Plug heater hoses and core fittings to prevent coolant spillage.

3. Remove bolt located below windshield wiper motor, attaching left end of plenum to dash panel.

4. Remove nut attaching upper left corner of evaporator or heater case to dash panel.
5. Disconnect vacuum control system supply hose from vacuum source, then push grommet and hose into passenger compartment.

6. Remove all instrument panel retaining screws and pull instrument panel back as far as possible without disconnecting any wire harnesses.
7. Loosen right door sill plate and remove side cowl trim panel.

8. Disengage temperature control cable housing from bracket on top of plenum. Disconnect cable from temperature blend door crank arm.

9. On models w/Automatic Temperature Control (ATC) , remove cross body brace and disconnect wiring harness from temperature blend door actuator and disconnect ATC sensor tube from evaporator case connector.
10. Disconnect vacuum harness at vacuum connector near floor air distribution duct.

11. Disconnect white vacuum hose from outside recirculating air door vacuum motor.
12. Remove two hush panels.

13. Remove one plastic push fastener retaining floor air distribution duct to left end of plenum. Remove left screw and loosen right screw on rear face of plenum. Remove floor air distribution duct.

14. Remove two screws from rear side of floor air distribution duct to plenum. To remove right screw, it may be necessary to remove the two screws attaching lower panel door vacuum motor to mounting bracket.

15. Remove push fastener attaching floor air distribution duct to left end of plenum, then remove floor air distribution duct.
16. Remove two nuts located along lower flange of plenum.
17. Carefully move plenum rearward, so that heater core tubes and plenum case upper stud clear openings in dash panel, then remove plenum from vehicle by rotating upper portion of the plenum forward, down and out from under instrument panel. It may be necessary to carefully pull lower edge of instrument panel rearward while plenum is being removed from behind instrument panel.
18. Remove retaining screws from heater core cover, then the cover from plenum assembly.

19. Remove retaining screw from heater core inlet and outlet tube bracket.

Heater core removal and installation diagram.






20. Pull heater core and seal assembly from plenum assembly.
21. Reverse procedure to install.

Section 12-03: Air Conditioning System 1992 Town Car/Crown Victoria/Grand Marquis Workshop Manual REMOVAL AND INSTALLATION Plenum Removal

1. Disconnect battery ground cable.

1. Disconnect the heater hoses from the heater core tubes. Plug the ends of the heater hoses to prevent coolant loss.

1. Plug heater core tubes securely to prevent coolant leakage from heater core during plenum removal.

1. Remove three nuts located below the windshield wiper motor retaining the LH end of the plenum to the dash panel (Fig. 15).

FIG. 15 Plenum and Air Inlet Duct Removal

1. Remove one nut retaining the upper LH corner of the evaporator case to the dash panel.

1. Remove LH and RH lower instrument panel insulators.

1. Disconnect two vacuum supply hoses from vacuum source. Push grommet and vacuum supply hose into passenger compartment.

1. Remove all instrument panel retaining screws and pull the instrument panel back as far as possible without disconnecting any wire harnesses.

1. Loosen the RH door sill plate and remove the RH side cowl trim panel.

1. On manual systems, disengage the temperature control cable housing from the bracket on top of the plenum. Disconnect the cable from the temperature blend door crank arm. On ATC systems, remove cross body brace and disconnect wiring harness from temperature blend door actuator and disconnect the ATC sensor tube from the evaporator case connector.
   

1. Disconnect the vacuum jumper harness at the multiple vacuum connector near the floor air distribution duct.

1. Disconnect the white vacuum hose from the outside-recirculating door vacuum motor.

1. Remove two hush panels.

1. Remove one plastic push fastener retaining the floor air distribution duct to the LH end of the plenum. Remove LH screw and loosen RH screw on the rear face of the plenum (Fig. 14), and remove the floor air distribution duct.

1. Remove two nuts from the two studs along the lower flange of the plenum.

1. Carefully move plenum rearward to allow heater core tubes and the stud at the top of the plenum to clear holes in the dash panel. Remove plenum from vehicle by rotating the top of the plenum forward, down and out from under the instrument panel. Carefully pull lower edge of instrument panel rearward as necessary while rolling the plenum from behind the instrument panel.

Installation

1. Route the vacuum supply hose through the dash panel and seat the grommet in the opening.

1. Position the plenum under the instrument panel with the register duct opening up and the heater core tubes down. Rotate the plenum up behind the instrument panel and position the plenum to the dash panel. Insert the heater core tubes and mounting studs through their respective holes in the dash panel and the evaporator case.

1. Install three nuts on the studs along the lower flange and one on the upper flange of the plenum (Fig. 15).

1. Install three nuts below the windshield wiper motor to attach the LH end of the plenum to the dash panel.

1. Install one nut to retain the upper LH corner of the evaporator case to the dash panel.

1. Position floor air distribution duct on plenum. Install two screws and plastic push fastener.

1. If removed, position panel door vacuum motor to the mounting bracket. Install two retaining screws.

1. Connect the white vacuum hose to the outside-recirculating door vacuum motor.

1. Connect the vacuum jumper harness to the plenum harness at the multiple vacuum connector near the floor air distribution duct. Install floor duct.

1. Connect the ATC sensor tube to the evaporator case connector on ATC equipped vehicles.

1. Install the cross body brace and connect wiring harness to the blend door actuator on ATC equipped vehicles.

1. Connect the temperature control cable housing to the bracket on top of the plenum and connect the temperature control cable to the temperature blend door crank arm. Adjust the temperature cable as outlined under Adjustments.

1. Install the bolt to attach the lower RH end of the instrument panel to the side cowl.

1. Install the RH side cowl trim panel and tighten the RH door sill plate retaining screws.

1. Install glove compartment door and check arms.

1. Connect vacuum supply hose to vacuum supply.

1. Install RH and LH lower instrument panel insulators.

1. Install two hush panels.

1. Unplug the heater core tubes and connect the heater hoses to the heater core tubes.

1. Fill the cooling system with coolant to replace coolant lost during removal of the plenum.

1. Connect the battery ground cable. Check the system for proper operation.

The most likely cause is a failed blend door actuator; however I recommend a little troubleshooting. First, can you hear a clicking sound behind the dash when you turn the setting to hot? If yes, it is certainly the actuator stripping its gears. If not, check to make sure the heater hoses are both hot as they connect to the heater core at the firewall (in the engine compartment). If one or both of the hoses do not get hot, there is a blockage caused either by an air bubble or a stuck water control valve in the heater hose. If the hoses are both hot, the indication is again the blend door actuator.

Below are instructions for replacing the actuator. Look at the diagrams carefully--the big arrows point to the front of the truck and the actuator is on the side of the heater box above the outlet duct that runs to the driver's side of the floor. Also, the actuator is expensive, so I recommend you make sure it's bad and shop around a bit to get a good price. To check out the actuator, first see if you can turn the blend door by hand. If you can't turn it, maybe it's jammed. Also, reconnect the actuator after removing it and see what it does when you turn the heater to hot.

Removal & Installation

1. Remove the floor air outlet duct extension (1) from the floor duct (2).
   

   

Fig. Remove the floor air outlet duct extension (1) from the floor duct (2)

Disconnect the electrical connection at the blend door actuator (#10 in pic below).

Fig. Blend door actuator and related components

Remove the blend door actuator mounting screws from the HVAC module.

Remove the blend door actuator as an assembly with the actuator cam.

Fig. Remove the blend door actuator mounting screws from the HVAC module

To install:

1. Install the blend door actuator as an assembly with the actuator cam.
   1. Line up the heater/defroster valve lever with the blend door actuator cam slot.
   2. Line up the A/C valve lever with the blend door actuator cam
   
   
2. Install the blend door actuator mounting screw to the HVAC module.
   1. Tighten the blend door actuator mounting screw to 14 inch lbs. (1.6 Nm).
   
   
3. Connect the electrical connection at the blend door actuator (10).
4. Install the floor air outlet duct extension (1) to the floor air duct (2).

Picture of actuator:

This is most likely caused by a failure of the heater blend door actuator, which you can fix at home in about three hours (if you have small hands). The front heater is actually working, but the blend door is stuck shut by the failed actuator and is preventing the heat from reaching the dashboard vents. To get at the blend door actuator, you have to take the radio out. Behind it and built into the duct work of the heater is the actuator module, which you can remove and replace fairly easily. Good discussion here: http://www.automotiveforums.com/t389726.html

The blend door is stuck in cold position. That usually happens because the blend door actuator has failed.

You will need to test and replace the blend door actuator.

To replace the actuator you will need to take apart the dash and remove completely the instrument panel,d isconnect the connector, remove the four screws, remove the temperature blend door actuator and replace it.

The replacement is not a job for beginners, since you have to take apart the dash to access the actuator.

Regards.

The ducting to the left must be fed from the heater box. Yet the blend door must not be sealing allowing the cold air the blend with the hot. Check the blend door mechanism, behind glove box, or some dash panels may need to be removed to access this door.

You will need to replace the air temp control blend door actuator motor, it is located behind the dash near the heater core and AC evaporator core inside the air ducting system, the dash must be removed in most cars to replace this part or service the blend door which may be warped and jammed.

The heater and a/c blend door actuator motor is located behind the center of the dash just below the windshield. The steering column must be detached and lowered and the dash must be removed to access the blend door motor.