6420 heater stop working after new coolant

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wayneFFS

New member
I changed coolant recently and the heater has not worked since then. AC works fine. fan works, temp controls seem to work, definitly do for AC, ideas
 
I'm just guessing but wonder if it has air in the heater line... It may need "burping"?? This heats up from circulating hot water/coolant from the radiator and then a fan to blow the heat to the cab.Is this the type you have? Next, I would check the thermostat. also make sure that your rad is full still. But I am just shooting guesses around. Our old truck has a leak in the heater coil and you can smell coolant inside the cab.. Others will chime in soon. good luck, bordercollie
 
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Like Bordercollie says....you have an air lock in your heater hose and/or the heater core itself. I've found that loosening the connection on the return side while the engine is running (highest point if possible) will allow the air to bleed off. The heater is usually the highest point in the cooling system and that is where the air stays when you drain and refill your cooling system.
 
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