Sixto helped me out with a good trouble shooting guide Troubleshooting Mercedes-Benz 190 E/D 201 Tempmatic Climate Control System - Benzworld.org - Mercedes-Benz Discussion Forum .

I'm still working on just the heat with these symtoms;

Cold air is coming in around the radio / console area all the time. Not out of the vents when the switch is closed but somewhere lower.

Blower is squealing but wroking in all speeds.

Heat works when I've got it set to max. When I move it slightly below max, no heat at all.

Any thoughts or suggestions?

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You can't always get what you want, but if you try sometime you just might find you get what you need.

Aspirator motor for the temperature and vacuum pod for the floor vents.

Got to the blower motor yesterday evening. Couldn't get the bottom 2 metal clips loose to remove the heater box cover but iit would open up at the top about 4". Enough access to oil up the motor which stopped the squealing. For future reference since I doubt a good oiling is the permanent cure, how does one get to those bottom clips?

Any way, it was nice to drive in this morning with the heat blowing on the low setting which made it comfortable in the 30 degree weather.

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You can't always get what you want, but if you try sometime you just might find you get what you need.