W123 Climate Control Problem - full hot or full cold, no middle ground

[kyle242gt]

Hi all -

I have an 84 300D, 215K on it.

The problem: any setting above MIN on the ACC temp dial has hot air coming out.

I have run through the troubleshooting on the CD to the best of my ability. All switches, vacuum units, fan, aux pump, temp sensors, checked out. Monovalve has a new kit in it.

I disassembled the temp dial, cleaned the traces, reassembled - no change.

I'm considering adding a potentiometer to the ambient temp sensor, thinking maybe, just maybe, the ACC control unit thinks the car is colder than it really is.

I've posted about this on the BW forums in the past, but haven't gotten any help.

Crazy thought - is it practical to retrofit a non-ACC control unit? I find myself thinking if I could just rig a cable to the temp dial and put a normal manual water valve in, I'd be all set.

Thanks for any advice!