After having several problems with my Climate Control system such as AC randomly starting and stopping, center vents working sometimes, and sometimes not, etc. I finally took some of the advice offered here on this forum and did the following with the following results:

1. Unplugged the Aux Water Pump.
2. Pulled CCU and resoldered all connections. Put the unit back in and it seemed to work while driving around the neighborhood, but the next day had the same intermittent problems.
3. Pulled the CCU again, this time I pulled apart the temperature wheel. Found a lot of carbon build up on the little brushes. Cleaned this all up really well and reinstalled. Seemed to work again, but it quit a couple of times on the way home (108 degrees today).
4. Wiggled the temperature wheel and air starts blowing out of all the right places.
5. Stop by to check on my battery problem ( see other post). After restarting car, turn on AC and can only get air from the side vents. No amount of wiggling can get it to do otherwise

Could the temperature wheel be the source of some of these issues, or is my CCU fried, or is it something else. Sick and tired of sweating in my car.

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1989 300E
103,500 miles

1982 300SD
Sold but not forgotten

When you resoldered the pushbutton controller, did you just re-heat or did you remove the old solder and apply new? I believe this is especially important for the edge connections as re-heated solder tends to separate and become very brittle.

On another note, and possibility, I have noticed that if you are having voltage problems, i.e. alternator not charging, you will also have problems with the climate control as it needs a good reference voltage to maintain a temperature. I found this out myself recently, as my alternator or possible grounding problem is causing the battery to discharge. Once it discharges enough, the CCU will not maintain temperature. After an overnight charge on the battery, everything starts working like it should. Cure your battery charging problem and you may get two birds with one stone.

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Sam

84 300SD 350K+ miles ( Blue Belle )

I thought that you were supposed to only reheat the solder, I have another unit that I can remove and resolder the edge connections. Also, it makes sense that this might be part of the charging problem. Will try to find the grounding strap and check it out.

__________________
1989 300E
103,500 miles

1982 300SD
Sold but not forgotten

The wheel is just a pot, I doubt that's causing you problems but it can be checked easily with an ohm meter.

Have you checked all your vacuum actuators?

Danny

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1984 300SD Turbo Diesel 150,000 miles

OBK member #23

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