Driver Heat Damper, bypass?

Neill1022 · Post by **Neill1022** » 17 Nov 2011, 17:38

Hi, I am having trouble with my drivers side damper door not opening. Has anybody tried to "rig" the damper? Specifically applying voltage to the motor to get it to open? Has anybody removed the motor and turned the damper with success? I wouldn't mind heat all winter (It's cold from Nov-April here) and by then I could have some money to get it fixed right, thanks!

Post by **Ozark Lee** » 17 Nov 2011, 19:33

Normally the problems are more mechanical than electrical with the damper motors. From my experience the damper motor shells out a gear or the shaft splits. The only way to know for sure is to remove the damper motor and give it a good "look see". For the driver's side just remove the lower dash panel (three T-25 Torx screws and then the stiffener behind the carpet to get to the motor on the side of the climate unit. There is one other Torx screw that you need to remove to get the stiffener out that is about halfway down the console but I can't remember the size - it seems like it is a T-15 Torx head.

Once you remove the motor any mechanical damage to the gear or the shaft should be obvious by just looking at it. If the motor broke a gear you are pretty much looking at just replacing the motor but there are a number of creative solutions to the split shaft in the repair database. One of the most ingenious was to slice a .40 caliber pistol shell apart and use it as a shim to hold the otherwise broken shaft back together. Having all of the parts of the shaft and some epoxy also helps along the way.

...Lee

Neill1022 · Post by **Neill1022** » 17 Nov 2011, 20:35

Thanks Lee, I'll give it another go. It's hard to get my Popeye forearms up into where they need to go, any suggestions to make that easier? Knowing the bolster comes out would make it easier, any other little trick you could pass along just to get at that sucker would be much appreciated!

Klausc · Post by **Klausc** » 18 Nov 2011, 09:59

I wouldn't run the motor with a 12V battery. That can break the 'stop' inside and render the motor worthless. Then it would be off to a junk yard to get a new one. Most likely it is the shaft connection that failed. Because it failed in the cold position, set the controls to cold before moving the motor. That will avoid recalibrating the system, which is a major pain.

If the yellow lights are blinking, read the codes in B-1, clear what you can and see what else is wrong. A bad driver side temp sensor will give you the same problems.

Neill1022 · Post by **Neill1022** » 18 Nov 2011, 16:09

Thanks Klaus, good info. I read the codes and yes, sensor failure as well so I'm trying that first, but the pass side reads same, but no problem on that side. I tried clearing the codes and followed the instructions to the letter, but they still wont clear, I take that as reading the same problems, should they clear and come back more slowly?

Klausc · Post by **Klausc** » 19 Nov 2011, 10:40

If the sensor codes will not clear, try pulling the dirt out of the sensors - behind the grab handles - with a vacuum cleaner nozzle. Enough dust curls will stop the little fan from turning. If the sensor codes = a short, the sensor might need to be replaced. I would work on the sensor before pulling the vent motor, unless there is a code for that also.

Neill1022 · Post by **Neill1022** » 19 Nov 2011, 12:26

Thanks Klaus, I pulled the sensor and pulled out about a quarter cup of dust, is there a re-set procedure for the ACC? I thought I caught that in an earlier thread.

Klausc · Post by **Klausc** » 19 Nov 2011, 14:12

You only need to do a reset if you replace a vent motor. It takes about 20 miutes of driving time and is a real pain. Just try clearing the codes again and see if the temp sensor works again. I have a Pocket Data Book with all of the codes, if you cannot find the definitions.

You will note that the orange blinking lights of death will stay green if you put both blower and vents in auto mode, after the codes are fixed. Possibly better air circulation?

Post by **JimBee** » 19 Nov 2011, 14:34

The first problem I had to solve when I bought my first Volvo (850) exactly 3 years ago was cold feet on the drivers side.
That's a problem of the damper not opening.

When I pulled the motor (right side of heat column that houses the damper), I immediately saw the shaft was split at the end. I'm not sure what the engineer who designed that one was thinking but it seems destined to fail because the input shaft is square shaped and goes into a square hole in the end of the PLASTIC damper shaft—which if I remember right is only 10 mm diameter. If the damper resists moving, the input shaft turns and splits open the end of the shaft. Mine had the split piece hanging there, so it was a matter of cinching it back together.

If that's your problem, basically, you need to get a collar on that shaft that exactly fits the shaft and is long enough that it won't slide away from the input end.

I found some 10 mm I.D. bushings that I think were also 10 mm long. They exactly fit over the shaft and I think two of them exactly covered the length of the shaft, so 20 mm long. Put it back together and it has worked fine through 3 winters (knock on wood).

Neill1022 · Post by **Neill1022** » 19 Nov 2011, 15:09

Thanks Jimbee, that gives me a good idea of what to expect. So the square peg fits in the square drive shaft but splits when there is resistance on the damper door. Hold the split end together and it's good to go. Thanks for the sizes as well. Is it possible, once I get to this point, to turn the damper by hand and opening the door? I want to be ready for anything (needs new motor for example) and with only so much daylight to work with, I may have to set it and finish it another time.
Thanks again guys!