I had my heater repairwd in my 1996 Chevy blazer, a heater control valve and an actuator. The air is warm and not hot. When I looked the parts up I was told there is no such part as a control valve.
it may not have a valve that controls hot water flow, but it needs a valve or switch to divert the duct work flap door to flow air thru the hot heater core and in the cabin, The question for low heat is ,,how hot is the water going thru the core and flow rate
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