I bought an 82 300TD with the climate control not working (no switches do anything. nada.)

I pulled off the panel for the switches and poked around a bit, unplugged a few things, plugged them back in, nothing seemed out of the ordinary. Still--didn't work.

Today at lunch, I started the car and--miracle of miracles--air is blowing out of my vents (set on defrost, fan on high)! A bunch of dust too, from months of no use.

Tonight, I started the car again and...nothing. No fan, no air, no amount of button pushing makes the thing come to life. When the car is running and I switch from the defrost or vent buttons to the empty circle (off) button, I hear a clunk from behind the instrument cluster area. When the car is not running, no clunk.

Any ideas?

The problem sounds like it could be the key switch. After I start my 300td, I have to turn the switch back just a little to get the cc to function.

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a few mb diesels

I had the same thing happen (the reverse actually, mine usually works). Great to hear if anyone has figgrued this climate control widget out (it's expensive to replace too!).

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Obiwanrazzy
1985 300D 267k and hemorrhaging...

Well, I was hoping it would just take a little key jiggle/turn back...that would have been great. But it didn't work.
Darn.

It's happened once again--at defrost the vent worked, but when I changed to a different venting feature/button, the blower cut out, not to return in any way...

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marshall

1982 300TD (220,000 mi.)

Defrost is usually the last setting to go on these for some reason. On mine I replaced the puchbutton controller with a known good one and it restored full function to the ACC system.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

Symptoms are consistent with cracked solder joints in the CCU.

CCU? Climate control unit? Do you mean miscellaneous solder joints throughout the system (or, more likely, in one place?).

It would be great if I had a spare working switch module, but I don't. Have to go find a parts car somewheres...

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marshall

1982 300TD (220,000 mi.)

Yes. the "push button" unit.

The solder joints tend to crack where the connectors attach (at a 90 degree angle) to the ends circuit board. It will be obvious if you open the unit and look at it. Reflowing the joints is usually all that is needed.

"Tangofox007":

You nailed it. Cracked solder joints. Only about three of them were cracked, but I guess that's all it takes.

I imagine a lot of CCU's get replaced for this problem. This is a much cheaper fix than I had hoped for.

Thank you so much!

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marshall

1982 300TD (220,000 mi.)