The heater is not working

2012 MERCEDES BENZ 220CDI
140,000 MILES • 2.1L • 4 CYL • 2WD • AUTOMATIC
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MUNE111
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Hello and thanks in advance. So, the blower is fine on full speed but when you put the hot side one it still comes cold air. I've changed some parts Like thermostat, radiator drained and cleaned, water pump circulation and the pipes that go on to the heater are still cold while temperature is 90 degrees.

Any idea?
May 9, 2022 at 1:11 PM
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STRAILER
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There is an auxiliary water pump that sounds like it is not working, which is common in these cars, but to make sure you can remove the pump and put power and ground to it to see if it is working. Here is the location of the auxiliary water pump which is under the hood in the diagrams below. Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.
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May 10, 2022 at 9:46 AM