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!