2nd Gen Non-Engine/Transmission HVAC Blend door actuator Servo

[RBallard]

I am looking for an HVAC component known as the A/C temperature door actuator servo. P/N 5104879-AA. The service manual refers to it as the blend door actuator. I visited the dealer this weekend to check on price and availability. As the parts person was showing me the screen, he clicked to the screen showing pricing. I guess he didn't think I saw it, $62. 50 dealer cost, $105 MSRP, which is exactly the price he gave me. I really don’t want to spend a $100 bucks not knowing if this will fix the problem or not.



HVAC only works in the extremes - You have to move the dial either all the way to the HOT side or COLD side to get the blend door to move. The work around for me is to move the selector to the middle position (12 o'clock) as luck would have it, this stops the blend door. The service manual says to move the selector to the middle position, unhook the batteries, and install the unit, which I have already replaced the HVAC selector housing, and followed the procedures. When you hook the batteries up the blend door is supposed to move to the extremes and determine center. This didn’t happen and the only other thing I can think of is that the servo motor isn't worth a hoot.



I also had problem earlier where the HVAC would blow hot for a while then cold, then hot and so forth. Turns out that the blend door and actuator are keyed with a plastic key. This key ended up deteriorating over time and the servo motor, if it can't find it's stop, will reverse thus causing my hot and cold air.



The housing is located under the passenger side dash. 2 screws hold it in place. It simply unplugs and slide off the blend door shaft.



Bob

 

[bmoeller]

Is it vacuum actuated? If it is, is it getting any? Is there a blown fuse somewhere? Problem with the switch?

 

[RBallard]

The top switch is vacuum operated and functions properly, the lower switch is electronic.

 

[NevadaBackroader]

I've had problems with my heat/ac since day one. First, the control didn't control. It was stuck on warm. The dealer replaced the blend door and got the AC working, but the control would only go full hot or full cold. Dealer replaced the control which didn't fix the problem. It gets really irritating having to move the control one notch to heat and one back to cool all the time trying to maintain an even temperature. Any ideas? My dealer is clueless. Now the dealer says it is out of warranty at 40k when I have a 70k extended "bumper to bumper" warranty. On top of that, it's really hard to take care of this stuff from Iraq!

 

[RBallard]

That's exactly what I am doing, one notch forward or back and I had the same thing, did't work from day one. I should have taken it in I just thought I would do it when I would have to take it in for something else which hasn't happen. I have replaced the controls and that didn't fix it. I followed the directions in the service manual because it sounds critical in order to have the door function. I would have thought that the motor is nothing more than a step motor and that by moving the swith one way or the other would step the motor. If the motor moves to the extremes, I can only get to move by going to the other extreme. Once it's moving I can stop it by returning to center and then move it to the left or right will adjust it but you have to move the dial to center to get it to stop. I am in the process of locating a new servo motor and will let you know if that finally fixed the problem.



I don't understand why that's not covered under your extended warranty.

 

[NevadaBackroader]

Thanks, I just talked to my wife over internet phone (gotta love the technology). She's going to try the center stop. As I recall, we were going just one notch from full hot to full cold with no center. Yea, she is contacting DC on the warranty issue. I read it to mean the only things not covered were tires, brake pads, and clutch disc. So, the control is supposed to take the place of a synchro motor? sounds like a lot of extra stuff when just a lever and cable would do the same thing. It wouldn't be that much of an issue if there was a way to turn it off and still get fresh air into the cab to keep the windows from fogging. If it fails again after the warranty is up, I'm going to look into some way of mechanically controling the blend door. Thanks for the reply.

 

[RBallard]

It's fixed

I bought a used blend door actuator ($50) and installed it tonight. After reconnecting the batteries and keying on the ignition, I immediately saw movement from the actuator. The servo now moves with each click.



NevadaBackroader, this must be the cure.



Bob

 

[Blu-meanie]

NevadaBackroader... ... ... thanks for serving our country... ... . hope all is well

 

[NevadaBackroader]

Thank You for caring. My soldiers have been extended over here. We were supposed to go home in January, now it looks like May. I was concerned that a few would not come back from leave in December and January, but the overwhelming support and gratitude they encountered during their two weeks at home encouraged them to do the right thing and come back to finish this tour. One of them lost her plane ticket and bought a connecting flight to Baltimore. She was even upset that she was delayed a day in Kuwait.

 

[NevadaBackroader]

And on it goes: My wife took it in for an oil change at the dealer... . They said since the blend door has been replaced once and we didn't get it back to them within so many miles, it is now not under warranty any more. We have records showing we have mentioned it at every oil change... . What's the number for DC?