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No interior heat?

1241 Views 5 Replies 3 Participants Last post by  SilverDiesel
Hi all,

my ride is an 85 300d

I've been trying to figure this out for sometime and now that it snowed last nite it's become a bit more urgent.

I get no heat at all not thru the vents or defrost

I've replaced the monovalve, and the coolant is filled to the arrow.
blower is strong still just cold air all the time.
I also checked the aux pump and that seems to be humming right along when it's getting power. checked the power going to the monovalve and there is power there as well.

if it's the heater core how do I get to that? do i have to remove the entire dash?

thanks in advance for any input.
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Under the monvalve inside the housing is a plastic ball, if it gets stuck you will have no heat.

Also what does you engine temp get to on the gauge in the cluster?
My -no heat- was the climate control servo....bought the bypass from Mercedes Source....took maybe 45 mins to install and now Im toasty and NOT $500 poorer!!!!
He doesnt have the servo, he has the later style and when it goes bad you get heat by default as a safety. Sadly though its still not working so im thinking its something else.
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