I have a 2000 ML430 and the temp in chicago is about 20 degreeF. I have noticed the coolant temp gauge fluctuate between a little below the 80 mark to abouth 90mark. (77degreeC to 88degreeC). Is that the way it should be? Or is my thermostat bad? Also, I set the climate control temp dial to the middle and it blows out super hot air for ~5minutes after the car has warmed up, then it gradually goes to cold air, and i have to start turning the dial to the right.... is that the way it is too? Please advise....

Yes.

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John Shellenberg
1998 C230 "Black Betty" 240K

http://img31.exs.cx/img31/4050/tophat6.gif

They all do this. Its the MB semi-automatic HVAC system

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...Tracy

'00 ML320 "Casper"
'92 400E "Stella"

Thanks for all of your input!!!