Well, my A/C stopped working about 6 years ago on my 300D.
I let it go because of fear of $$$$$$expense. My city is cold anyway.
About 2.5 years ago my heater went out and I let it go for close to one year.
Finally got the Klima servo replaced and the heat came back.
However, it had developed a constant trace of passive warm air at the
windshield vent.
Today, I finally had my mechanic check this neglected detail.
He quickly inspected the A/C amp (booster for climate control-000-85-0157). It needed replacement because the circuit board had some burn marks.
He smelled this, I could not. He must have a dog's olfactory!!

Anyway afterward the air vent worked with cool air going
and no more passive warm air, or hot air when the air blower was on.
Later ,I decided to flick on the A/C switch just for the heck of it.

Lordy, lordy, it worked!!

Cheap fix!!

Way cool

__________________
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