Chevy truck heater issue

[sambo73]

I have a 2002 Chevy Silverado 1500. My heats not working. It was low on antifreeze so put some in it. Now when you turn it on, blows cold air still. When i turn ac on and turn temp knob all the way to heat, the temp stays the same. That knob has always been weird. When you have it on the coldest setting, it would blow cold, but if you moved it 1/2”, it blew hot. There was no adjusting the degree of coolness.....any ideas?


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[stinkbelly]

My 04 had the contacts in the temperature controller go out. I had to go buy a new (rebuilt) one from Oriley. It was easy to install.

[jtd498]

In my case it was a plugged heater core.
Reverse flushed the heater hoses and was able to dislodge the gunk buildup; blew hot after that.

[sambo73]

It was like one minute it blew hot, next minute it didnt.


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[sambo73]

My 04 had the contacts in the temperature controller go out. I had to go buy a new (rebuilt) one from Oriley. It was easy to install.

What did the part cost?


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[BolilloLoco]

Blend Door Actuator
Thermostat Control Knob
Plugged heater core

[BowSlayer]

My 2000 did that and the heater core was plugged. Like was stated, reverse flushed it and back to hot.

[KDinTX]

If the heater core isnt plugged, you can try a blend door recalibration on it. Basically pull the hvac/ac fuses, turn truck on and off, then put fuses back in and upon start up it will full sweep the blend doors. I had to do this on my wifes tahoe to find the blend door that quit and replace it. If it doesnt have dual zone climate, there should be 3 blend doors, one beside the drivers side under dash, one behind the glove box and one up high behind the dash. Her tahoe had 4 and it was the one on top of the system for dual climate.

https://www.gm-trucks.com/forums/topic/81984-hvac-doors-out-of-calibration/

[sambo73]

Thx, ill try flushing the heater core first.


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[stinkbelly]

What did the part cost?


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I think it was about $130.

I forgot about the blend door motor. I had to replace that once. It was easy if you can stand on your head.

[sambo73]

Flushed the heater core. It was clean.


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[35remington]

Could be your blend door actuator is stuck on cold.

[sambo73]

Could be your blend door actuator is stuck on cold.

Kinda what im thinking


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[COACH_EM_UP]

Mine 2007 does the kind of the same thing. When I turn the heat up to 90, then I get hot air, but when I back it down to 80 or 78, it blows cool to cold. If I want hot air, then I have to crank it up to 90 on the thermostat. Any idea what could be causing this?

[manwitaplan]

Mine 2007 does the kind of the same thing. When I turn the heat up to 90, then I get hot air, but when I back it down to 80 or 78, it blows cool to cold. If I want hot air, then I have to crank it up to 90 on the thermostat. Any idea what could be causing this?

My 2014 is doing the same thing. Chevrolet 3500. I have cold or hot nothing else. I have to get it to 90 to get the heat rolling.

I hope someone else can explain what to look for.


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