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No Heat.

Hardware

Member
Messages
9
Location
Cumming, GA
I have changed actuator door for the blend. I have tested the other 2
and all actuators are working. I have reprogrammed. I have replaced head unit and reprogrammed.
I had to get it passed inspection’ was throwing a P0128 code’ it was coolant sensor or thermostat. I replaced
coolant sensor and got passed inspection. There appears to be light pressure on coolant hoses’ when motor is hot, could thermostat be stuck open and not pushing hot coolant through heater core? it does appear to be running pretty cool.
 

alrock

El Diablo
Staff member
Messages
10,442
Location
Scottsdale
No heat ever, even after engine is at operating temp, approx halfway up temp gauge? If thermostat is broken and stuck open, it will still reach full temperature but will just take longer - maybe another 5 minutes or so. If it is just a thermostat issue then you'll get heat in something like ten minutes, not five.

If you are not getting significant pressure in the hoses, you could have an air pocket in the system or a leak, like a worn out radiator cap.
 

Hardware

Member
Messages
9
Location
Cumming, GA
No heat ever, even after engine is at operating temp, approx halfway up temp gauge? If thermostat is broken and stuck open, it will still reach full temperature but will just take longer - maybe another 5 minutes or so. If it is just a thermostat issue then you'll get heat in something like ten minutes, not five.

If you are not getting significant pressure in the hoses, you could have an air pocket in the system or a leak, like a worn out radiator cap.

Thanks for answer, thought I might have to burp system or something. The radiator cap looks brand new, but thought that could be next simple try. Wondering if something is blocking the door internally. Thought of trying to manipulate door with a wide screwdriver.
Next guess is thermostat replacement and diode install on control wire. Wondering if heater fire could be clogged but both sides of hoses are warm/hot. Puzzling because we did
have heat before.
 

4speedfunk

Well-Known Member
Messages
4,212
Location
Tardville
You may have air trapped In the heater loop. Try this test...
Get the truck warmed up. Crank the heat with fan on high. Stab the throttle from a stop and accelerate quickly...see if a burst of hot air comes out of the vents. Try the same by braking hard. The g-force of accel or decel will make the water displace the air bubble momentarily. The heat will usually go cold within a minute, as the air bubble returns during normal driving. If this happens...you got air trapped in the cooling system. Use a vacuum fill kit to purge the air. You can also try parking with the truck nose up on a very steep hill and filling the radiator and letting it sit overnight.
Like most newer vehicles...the H3’s radiator fill is not the highest point of the system, so anytime you drain it to do work...air can easily get trapped.
 
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