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Old 11-06-2012, 09:31 AM
mbdoc mbdoc is offline
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Join Date: Mar 1999
Location: Tucker, Ga USA
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The only coolant temp that needs to be hot is the top hose & the heater supply hose.

On that truck, there isn't a heater valve & coolant is always flowing thru the heater core.

To see if the blend air system is working, you need to remove the glove box liner & with the ML running move the temp dial back & forth & then watch the blend air flap move.
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