Running Heat with Coolant Flush

[galaxy]

So this is totally just a question to start a fun/dumb conversation...but why do people run the heat on high during a coolant flush? Running the heat (fan) on high has absolutely nothing to do with when or how much coolant circulates through the heater core. It's the same flow all the time. The heat in the car is controlled by mixing doors and fan and such, but coolant flow to the heater core is constant. Thus, running the heat has no influence on circulating coolant in an attempt to bleed or flush the system. At first, I thought maybe it's a holdover from the old days like 3,000 mile oil changes, but looking back, that's not even true. It wasn't any more accurate then than it is now. Anywho...cheers.

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[cerbomark]

 

[Basspro302]

We do it to make sure the car has no air pockets in the cooling system after the flush. Heater cores are often the highest point in a cooling system so we like to verify the car has heat and no air pockets. Some cars do have coolant valves to shut off coolant flow to the heater core.

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