OK I searched the archives and found some hints about bypassing the servo on a non-turbo 300D. Also some reference to the digital acc control and the other bypass kit.

However, I read several variations of climate control functions working or not working or uncontrollabely working as a result of a servo bypass etc. (not the digital bypass).

Question. How exactly does the ACC Servo function in relation to the dash ACC control unit and the CC amplifier?

For example, my 1979 300D servo seems to be internally frozen such that it causes an electrical drain on the battery unless the CC amplifier is removed.
Of course the car got no heat with this bad servo and good amp.
My dash CC unit buttons all operate to power on/off the blower and appropriate vents work for defrost and air. Just no heat.
My Air conditioning unit switches on with the dash switch even though the CC amp is now removed.

I am trying to figure this out.

It will help me assess which route to take.
Simple bypass or digital unit. Not interested in another servo unless the replacement is cheap i.e. expect it to last 9 months!

What I am leary of is doing one or the other 'fix' and later getting some other associated climate control problem which will defeat the 'fix'. esp. if the 'fix' is expensive.

SO, what are the mechanics of this torpid system?

Anybody know??

Best.

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
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1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD