Recently purchased an '85 300SD. Got the heater and AC working. But now it's stuck in one mode. Temp will change, but it just shoves all the air up through the defroster vents. No matter what buttons I push, none of the doors/valves open or close to direct the air to the correct outlet. Took the center dash apart and everything looks to be connected and in decent shapebehind the control console. Anyone have any ideas to send me towards? Thank you in advance for any help.

 

It could be very well your Climate Control Pushbutton Unit. Very easy to replace. I think I do have a very clean sharp looking one available.

 

Thanks. How much?

 

There's a control module that takes the elec signal from the CCU and opens the solenoid(s) to the vacuum that is used to control the podthat movesthe internal vents. Sounds like the vacuum is missing (maybe just a bad hose) or themodule is bad or all or some of your pods are bad in that order. The pods can be rebuilt with diaphrams sold by a man named George Murphy (not me or related)for less than $10 per, I redid mine last year and it works great. Get a CD manual (ebay or some people on MB sites sell them for $5 to $30) and it tells all about the CCU and where the parts are located. Buying parts to replace until it's fixed can be expensive. That is how some shops do it though.