OK folks, I have a 1982 Mercedes 300D turbo, 205K miles, and climate control issues. I have read most (if not all) of the entries but need some advice. Here goes:

I am getting hot air from the A/C vents. The car usually starts with cool air (A/C on) but then turns to hot shortly!

I did have a siezed auxilary water pump, and it has been replaced and now has a 1 A fuse. It is working properly (I think).

I have put in a new (inside) to the monovalve and I think it is working properly. The wire to the top of the monovalve is giving 13 volts when on max cool (engine running).

I have removed and checked the in-car temperature control sensor and found that it does give the correct resistance readings according to the MB service manuel on CD. (That little thing was a B**** to get back in and connected!) The hose from the guage to the blower motor is wrapped foam and has just been replaced.

I have cleaned the temperature control wheel and it seems to be working fine. The fan control is good, all buttons work as they are supposed to.

When set a max cool, I hear the compressor start but still get hot air. When first started in the morning, the air is cooled but warms up quickly.

I can block the aux pump hose to the heater core with vice grips and get cool air from the vents. I say cool because it runs in the mid to upper 60s from the vents; outside air is mid 90s. It should probably be colder but for now at least I know the compressor is running. I do not see bubbles in the sight glass - but probably would not recognize them if I did.

I think I have fried my CCU, but am reluctant to buy a new one. The local junk yard has none. I am considering taking it apart to check from burned areas and/or crack in the solder. However, since I don't know what I am doing I havn't done that part yet.

From these symptoms, does it appear that the CCU has been fried and if so, would trying to re-solder the unit be of any benefit? I maybe not, what else should I check.\?

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