No heat diagnosis and solution, heat blend door servo actuator

[4by4runr]

Updated with solution and title change for reference.

OK: Update and solution.

Fixed for $12.95 at u-pull.
Adding procedure for anyone else that may be looking for this solution.

1. Remove glove box
2. Remove 2nd glove box. 4 screws
3. Remove lower cover. Black 1 screw. Disconnect wiring harnesses.
4. Remove black floor vent on the left. It will kinda pop off with some force.
5. Unplug wiring harness from heat mixing servo
6. Unscrew bottom front brass colored screw from mounting bracket.
7. Unscrew bottom rear brass colored screw from mounting bracket.
8. Push/shove/Pry mounting bracket to the right, you will expose 3 more screws that are more easily unscrewed than that 1 remaining mounting bracket screw. Yes you are bending the bracket, SHOULD be fine, it took me 5 minutes at u-pull of bending it back and forth rapidly so maybe 150 bends, to get it to break.
9. Remove these 3 screws. (there is a chance that the servo arms could be blocking 1 screw depending on where it failed. The tools I used to remove these were a 1/4' short socket that will accept a small Phillips bit turning by hand. You could possibly fit a small ratchet in there. If you have giant hands, this part may be tough but still easier than removing the furthest rear screw on the mounting bracket.
10. Remove the servo/housing. So the orientation will be to have it start doing a backflip (counterclockwise rotation looking at the face from the passenger side) while pulling it up. There are 2 kind of legs that will complete it's rotation when those are parallel to the earth. Then wiggle it.. just a little bit...you've got to wiggle it.. ok... a lot. and it should pop free down and out the front.
11. Install new $13.00 servo by reading this list backwards.



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Hopefully somebody can point me in the right direction here.

So going over monarch pass it got a little cold and I went to turn the heat on but nada.
I have checked:
Coolant overflow is at normal level.
Both the inlet and outlet of the heater core are hot at the firewall.
The engine is not overheating or underheating.
The fan is operating normal.
The mixing door that opens and closes above the cabin filter is operational.
There is no heat at any setting (vent, defrost, floor)

I don't know what to check next.??
Any thoughts are greatly appreciated

 

[nevada]

Hopefully somebody can point me in the right direction here.

So going over monarch pass it got a little cold and I went to turn the heat on but nada.
I have checked:
Coolant overflow is at normal level.
Both the inlet and outlet of the heater core are hot at the firewall.
The engine is not overheating or underheating.
The fan is operating normal.
The mixing door that opens and closes above the cabin filter is operational.
There is no heat at any setting (vent, defrost, floor)

I don't know what to check next.??
Any thoughts are greatly appreciated

sounds like the blend door actuator is bad. the door you are seeing move is the fresh air door. the blend door which controls the heat will be inside the heater box, you wont be able to see it.

 

[Trent]

I just changed the temp control actuator on my '04. It's a tough job but can be done without digging too deep.

YouTube

You should be able to see it work when you adjust the temp up and down. New ones are about $160 on Amazon. Good luck

 

[4by4runr]

The problem is def the servo, I manually opened the door and viola, heat....

Ok so I got it out, opened the casing, cleaned the contacts and rebended them to apply more pressure to the contact surface of the large gear. Installed with the the wiring, seemed to operate clean and continuously without delays or stops so I finished reinstalling (so much fun), tested, no ac/only heat, took back off because I figured I have put the servo back in backwards, now no heat again.

So the servo is working but only reading to go one direction either fully open or closed depending on which way the servo is installed.

Does that mean I need to just clean the contact surfaces better since it's not reading one of the channels?

 

[Trent]

The problem is def the servo, I manually opened the door and viola, heat....

Ok so I got it out, opened the casing, cleaned the contacts and rebended them to apply more pressure to the contact surface of the large gear. Installed with the the wiring, seemed to operate clean and continuously without delays or stops so I finished reinstalling (so much fun), tested, no ac/only heat, took back off because I figured I have put the servo back in backwards, now no heat again.

So the servo is working but only reading to go one direction either fully open or closed depending on which way the servo is installed.

Does that mean I need to just clean the contact surfaces better since it's not reading one of the channels?

On mine the little contacts had worn through the super thin traces of the ponteniometer. There was a dead spot where it was not making contact at all. Good luck