Quote:
Originally Posted by PreferVintage
How did you make that change, may I ask? My W123 is automatic and I have either high or low and nothing really in between. I have to hit defrost and then switch to other settings to get the fan on. Temp sensor is fine, and I haven't had the time to pull apart the dash to look at the blend door servos and such. I would prefer going to a manual system. The solenoid valve in the heater line is bypassed using a ball valve, since it doesn't cycle correctly to maintain heat in the winter or A/C in the summer...like I said, an automatic system problem I haven't had the time to hit real hard. I guess when we collect more than one car, we pick and choose our battles given limited time and money!
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It's a bit time consuming, but basically I removed the dash first, then R&R the entire box, controls, and AC housing with a manual system from the same year 240D. The automatic CC wiring harness is mostly separate, so not too problematic. As I remember, there were only two leads that I had to cap off. It was much easier to use a thermostat from a W115 while retaining the original W123 on/off dash compressor switch than to use the 240D thermostat system. Then all the vacuum lines and "evil servo" and associated water lines were removed as well.
I would guess that your problems stem from either the evil servo or a combination of the solenoid valves. The CC water pump also contributes to lack of heat problems. I can't offer much else on repairing this system, but there are others here who have successfully worked on it. Your way of thinking about this horrible system appears to be the same as mine - replace it with manual and have done with it.