I have noticed that when I push any of the climate control buttons, the fan will spin but sound blocked. No heat will come out of the holes on the side.

I get the impression this is a bad vacuum pod, but where would this guy be located?

Search was not particularly helpful :/

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-Typos courtesy of my mobile phone.

Try it in AC and vent mode and see if there is air coming out of same vents.. or not ...

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

I found a mouse nest in my blower, both in my car and my truck..... might be worth pulling it and taking a peak...

Maybe the "main" flap that changes over from exterior to interior air and the recirc flap are out of sync? I think they're both in the passenger footwell or behind the glove box.

Pics here: 134 and 135. Hard to get perspective, but you can see the TXV from the A/C and the blower motor for locations: PeachPartsWiki: Replacing the A/C Evaporator