i have a Cummins. change heater core no heat . installed flush t and flushed no heat. not over heating. thermostat is working as well as the water pump. AC works . by pass door works. read that the AC/heater fan switch could be the culprit, because it actuates the AC compressor and a motor that switch air from heat to the evaporator. i do not know how to test the switch . any thoughts would be appreciated. driving around with a propane heater is getting old.
Feb 9, 2017 at 6:05 AM
