1992 300-E M-103 40,000 miles block & radiator have been drained twice every couple of years. With heater control wheel to full and car warmed up I am geeting heat at the front defroster vents and some at the two end vents for passenger and driver.
It seems like a blockage may be causing not all the heat to reach the passenger compartment.
Any recommendations would be welcomed.

Bob Geco
1992 300-E

If you disconnect the wires to the heater valve you should get full heat. IF not, either the valve is stuck partially shut or the heater core is plugged.

__________________
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Also check the auxilary circulator pump..