The car is a 1984 300D turbo, the a/c is working great with a brand new compressor and r12. The problem is every now and then when the a/c is on it smells funny, like a fishy smell. The taurus I used to own started to smell bad right before the heater core crapped out. The only difference is, the benz only does it every other day for about 2 mins then goes away. Anybody know what this is?

It sounds like you have some mustiness in your AC vents, old condensation sits in there and goes stale. It doesn't smell like anti-freeze, right?

After you ensure that the condensation drain is clear and draining properly. Spray Lysol down into the vents as best you can to kill the little germs that are causing this smell.

Also spray it or Febreez into the intake near your feet with the blower on...

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

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

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

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