Hey guys!

Back once again - just reviewed everything I could find on the 300sd CCU / Air Conditioning threads and I think I've discovered a new (and interesting) problem.

Two summers ago, I had a good mechanic friend go through my 1982 300SD's climate control. He replaced two vacuum spheres, soldered up the CCU, replaced the dryer and pressure switch and wala, I had AC. That lasted until fall, where I assume there was a small leak and once the refridgerant slowly leaked out, the compressor stopped. All buttons still worked, defrost, up/down with A/C, down with A/C, EC and of course, off.

Here's the interesting problem: only half the buttons work, now. I've replaced the CCU with a 'new' unit, one that came out of a car with fully operational climate control. Same part numbers. Defrost, and Up/Down with A/C work; the other buttons (with the exception of OFF) seem to do absolutely nothing.

The reason for the posting is it's getting warmer, but not too warm here, and I'm about to recharge the system - when it's cool at night, I'd love to just use EC and save the gas (err..diesel) when driving home from work. Soo..that would require all the buttons to function.

Anyone else experienced this? I've checked the usual culprits (fuses, etc). Other than the two buttons not working, system runs fine - heat is great, fan steps as it should. The old CCU had the same button issue - so it's clearly not the head unit.

Perplexingly yours,

-James