I have no heat in the cab. I have electronic HVAC. First thing we inspected was the blend door and it moves fully from heat to cool perfecty. We then reverse flushed the heater core and a bit of brownish material came out and flow appeared good. We also replaced the flow control valve heading into the heater core just in case. Cheap part to replace. Just ran the car up to temp. Cooling fans kick on when needed on the rad, so everything was up to temp but still no heat. Double checked the blend door. All good. I have no idea when I lost the heat as almost never drive the car on cooler days. Thank you

 

Have you felt the heater hoses at the firewall with the car running warmed up with heater controls on? They should be hot to the touch, if not the water must not be circulating. If the thermostat is working correctly and the water pump is good? I would check the water flow to the heater in and out of the engine for any restrictions. If all of that is good it should work.

 

Thermmostat is new, but could have failed. Yes that is my next step. we are leaning towards the pump area. I dont think the lines to/from the heater core were all that hot.
thank you.

 

I wonder about the water pump, impellers have been known to go bad but it's rare. If you have a water pump issue I wonder why the engine is not overheating when you're driving. An easy way to check water pump movement is to loosen or remove the water reservoir cap, start the engine cold and with your fingers squeeze the radiator hose from the thermostat to the radiator with the engine at 2K rpm and see if you can feel water rushing through the hose. If you do that would mean the thermostat is stuck open. But you say the engine reaches operating temperatures which would suggest the water pump maybe spinning the impeller on the shaft. Try the water flow test on the top radiator hose again at operating temperature by wrapping the hose with a rag several times and squeeze it like you did when cold and see if you can feel water movement. That should give you an idea if the water pump is working or not. At 2K there should be a good rush of water if working properly.

 

Thank you for the reply and yes i totally agree with what to check next. Gotta be a flow issue somewhere. Love working on these with my friends and we will figure it out and poet our findings. Unfortunately don't have a real garage currently to do this. But I'll figure it out. Thanks again.