First Thread! 2 AC problemas..
 

Hey Everyone!
Been reading a lot on the forum and there is some great info! I have tried the search function and can't quite find the answers I am looking for.

Anyway, we are proud new owners of an '85 300TD. Been redoing quite a few things including brakes all the way around, center driveshaft bearing, and of course lots-o-vacuum problems.

Just dropped about $900 on the AC system and it's finally working (kind of). The first problem is when the air is blowing, so is the heat. I can clamp off one of the heater core lines and the system cools down nicely. I am guessing it's in the control box under the dash (where the center vents are malfunctioning), but I am not sure. Is this where I should be looking?

2nd problem is obviously the classic center vent issue. I have the glove box out and was wondering if it's possible to take the top half of the dash off (dash pad) or do you have to remove the whole dash? I plan on removing the push rod pin from the actuator to fix this issue.

Oh! What is the correct way to disconnect the vents? The shop disconnected the passenger and broke it, so now it's glued together and I can't get it back in snug.

Any help would be greatly appreciated!!

Try replacing the monovalve.

Monovalve repair takes about 5 min. This is the kit you will need: http://catalog.peachparts.com/ShopByVehicle.epc?q=1985-Mercedes--Benz-300td-Climate--Control&yearid=1985%40%401985&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6234%3AED%7C10000135%3AMBC %7C1518%40%40300TD&catid=242213%40%40Climate+Control&subcatid=242328@@Mono+Valve+Repair+Kit&mode=PD

First thing I'd do is measure the voltage to the connector on the monovalve. if it's got 12V AT the connector, then the CCU is working properly, and the problem is definitely in the monovalve. it could be seized in the open position, or the diaphram could be torn.
if there is no voltage at the connector, you must have positive and negative at the connector. don't measure positive at the connector and ground the lead to the motor... the ccu modulates ground to control the flow of heat.

Thank ya'll very much!
I will check voltage to the monovalve and go from there.

Cheers!

Monovalve definitely bad. I will see if I can scrap one off of another TD I know of.

Thanks for the help!