Anyone have some wiring diagrams for Merc Topaz heater controls? These
things are notorious for burning push button switches. I have a factory shop
manual and can you believe not ONE wire color or useful drawing. 100 bucks
for nothing. They refer you to a EVTM manual for those drawings. Which is
not included in the shop manual of course. And the dealer doesn't have
access to anything older than 1994 on his computer system.
Hello, I think i can look for old wiring diagram maybe 92's if that's
fine with you
Sure. Would appreciate it. I did find a bit of info on Autozone and was able
to temporarily bypass the defective switch so I can get the heater fan
running. It still does strange things like start the rad cooling fan when
the windshield is set to defrost. This is really weird. Is it possible to
somehow be connected with air conditioning? Is it standard to have the rad
fan cut in when the air conditioner is started? I know the assembly is
somewhat charred so perhaps there is a short across from air conditioning to
Anyway there is heat again so this isn't a panic situation any longer.
Eventually I hope to find a good used part in spring when I browse the junk
yards. I haven't got the wiring figured out for the rear window defrost but
that is less important. I will be away for next two weeks too.
For the rad cooling fan.... whenever any heater position that has air
blowing on glass is selected, the AC cycles to act as a dehumidifier to
reduce/eliminate fogging. Whenever AC is commanded, the radiator fan will
come on in order to draw air across the AC condenser (without this airflow,
the AC would be ineffective since the refrigerant wouldn't condense to a
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