Climate control stopped functioning correctly this weekend on my 2007 C350. Unable to get air through the ducts. Heat is there, and I hear the fan blowing, but air does not get through any of the ducts (top, dash, or footwell), save for the first few seconds (more below).
Searched the forum here for a while and got many good tips. I tried the test/reset by depressing the Front Defog-Recirc buttons simultaneously. At first it did not pass, but I think I was not simultaneous enough in my pressing. After sorting that out, it consistently passes: I hear the dampers gently (more or less) activating, and the flashing lights go out after 15 sec or so. After doing this, I am still unable to get air to flow through ducts; if I turn the fan up to its higher ranges, I can hear the air rushing to get out, but it has no open duct to leave from.
One more bit of info: Starting from fan off, turning fan on will cause air will flow from the selected duct for 3-4 sec, and then it fades out. As I mentioned above, if the fan is running at high speed, after 3-4 sec I hear the air trying to get out of closed ducts. I can repeat this 3-4 sec of operation if I first reset by turning the fan off. I can also get this 3-4 sec of operation out of the top, dash, or footwell vents, according to which one is selected. Given this, and the fact that it passes the test/reset procedure, it seems the stepper motor lever arms on the ducts are not broken.
So, is this what a bad Climate Controller Unit does? If so, I read in other posts here that this is an easier repair than getting at the broken stepper motor lever arms, but I did not find any further info on how to replace it. If an SDS readout is required to further diagnose this, I have a good German car indy I can go to, but if the symptoms are fairly straightforward, I am happy to proceed without it. Any advice is appreciated.
Searched the forum here for a while and got many good tips. I tried the test/reset by depressing the Front Defog-Recirc buttons simultaneously. At first it did not pass, but I think I was not simultaneous enough in my pressing. After sorting that out, it consistently passes: I hear the dampers gently (more or less) activating, and the flashing lights go out after 15 sec or so. After doing this, I am still unable to get air to flow through ducts; if I turn the fan up to its higher ranges, I can hear the air rushing to get out, but it has no open duct to leave from.
One more bit of info: Starting from fan off, turning fan on will cause air will flow from the selected duct for 3-4 sec, and then it fades out. As I mentioned above, if the fan is running at high speed, after 3-4 sec I hear the air trying to get out of closed ducts. I can repeat this 3-4 sec of operation if I first reset by turning the fan off. I can also get this 3-4 sec of operation out of the top, dash, or footwell vents, according to which one is selected. Given this, and the fact that it passes the test/reset procedure, it seems the stepper motor lever arms on the ducts are not broken.
So, is this what a bad Climate Controller Unit does? If so, I read in other posts here that this is an easier repair than getting at the broken stepper motor lever arms, but I did not find any further info on how to replace it. If an SDS readout is required to further diagnose this, I have a good German car indy I can go to, but if the symptoms are fairly straightforward, I am happy to proceed without it. Any advice is appreciated.