Heater not working correctly?

Tiny
MARISSA BAER
  • MEMBER
  • 1995 CHEVROLET SILVERADO
  • 4WD
  • AUTOMATIC
  • 195,000 MILES
The heating is not working. We had changed both the heating core also put a 204 thermostat in thinking that was the problem. But had no luck with that. What could be the problem?
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Monday, October 30th, 2017 AT 10:30 PM

29 Replies

Tiny
KEN
  • ADMIN
It sounds like you have a temperature blend door actuator that is not working.

Here is a guide to give you an idea of what you are in for when doing the job:

https://www.2carpros.com/articles/replace-blend-door-motor

Here is a guide that will give you more options:

https://www.2carpros.com/articles/car-heater-not-working

Below is what it will be like for your car.

Please let us know what you find. I am interested to see what it is.

Cheers, Ken
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Tuesday, October 31st, 2017 AT 2:08 PM
Tiny
DAN_MAN12
  • MEMBER
  • 1994 CHEVROLET SILVERADO
  • V8
  • FWD
  • AUTOMATIC
  • 140,000 MILES
My heater is not blowing hot air. The fuse is good and the fan is blowing as it should. I can deal with that part but I think there is a problem with the heater core. I think it may be pluged up. I blew air through it and lots of rust came out. I am just wondering if air could pass but it still be too pluged to let water flow properly. Can you tell me how to go about checking this out and fixing this?

The heater core was cloged! I flushed it out and it now blows plenty of hot air! Thanks anyway!
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Monday, September 14th, 2020 AT 11:20 AM (Merged)
Tiny
BLACKOP555
  • EXPERT
Glad to hear you have fixed it.

And yes air under pressure can go through very minute holes and show flow, but water wont as its not under that much pressure.
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Monday, September 14th, 2020 AT 11:20 AM (Merged)
Tiny
ALASKADOC
  • MEMBER
  • 1994 CHEVROLET SILVERADO
  • 200,000 MILES
The button that switches the heater on is stuck on "cold air" setting so that is all that comes out is cold air. Can I repair this easily myself? If yes how? If you suggest mechanic should fix, what is the average amount it should cost?
Thanks, Nancy
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Monday, September 14th, 2020 AT 11:20 AM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Good morning.

When you command cold to heat and back, can you hear the mode door move in the heater case?

Roy
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Monday, September 14th, 2020 AT 11:20 AM (Merged)
Tiny
ALASKADOC
  • MEMBER
Yes.
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Monday, September 14th, 2020 AT 11:20 AM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Okay, so the mode door is working. We need to look at the cooling system.

Open the hood and go to the firewall where the two heater hoses from the cooling system go to the heater core. With the engine at normal operating temperature, are the hoses both hot to the touch?

Roy
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Monday, September 14th, 2020 AT 11:20 AM (Merged)
Tiny
NOHEATDUDE
  • MEMBER
  • 1992 CHEVROLET SILVERADO
Electrical problem
1992 Chevy Silverado V8 Four Wheel Drive Automatic 150k miles

No Heat, display, blower. Everything worked fine then the other day the digital display for my heat went black. The unit was repaced still nothing, the unit lights up with the headlights turned on but no display. Checked the blower relay switches, still no heat. Whats your solution. Thanks
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Monday, September 14th, 2020 AT 11:20 AM (Merged)
Tiny
MASTERTECHTIM
  • MEMBER


https://www.2carpros.com/forum/automotive_pictures/139033_no_11.jpg

chec the powe and ignition wires for voltage and then let me know
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Monday, September 14th, 2020 AT 11:20 AM (Merged)
Tiny
MASTERTECHTIM
  • MEMBER
Red wire and orange wire. My reply was chopped up
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-1
Monday, September 14th, 2020 AT 11:20 AM (Merged)
Tiny
KRAKER
  • MEMBER
  • 1992 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
I have a 1992 silverado k1500 305. I have no heat. Replaced water pump, thermostat, and rad, flushed heater core 4 times still no heat. Help!
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Monday, September 14th, 2020 AT 11:21 AM (Merged)
Tiny
KEN
  • ADMIN
Hello,

It sounds like you have a blend door actuator that is not working. Here are two guides that will help you see whats going on.

https://www.2carpros.com/articles/replace-blend-door-motor

and

https://www.2carpros.com/articles/car-heater-not-working

Check out the diagrams (Below)

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken
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Monday, September 14th, 2020 AT 11:21 AM (Merged)
Tiny
ANDREW NORMAN SR
  • MEMBER
  • 1991 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 200,000 MILES
My heater went out in my truck. I replaced the heater core and thermostat.
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Monday, September 14th, 2020 AT 11:21 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
If you still have no heat, allow the engine to warm up to operating temperature with the heater on high. At that point, feel both heater core hoses. One is a supply hose and the other a return hose. Both should be hot. If they are, suspect the blend air door is not functioning to allow the heat to enter the vehicle. If one is cold and the other hot, either there is a blockage in the system or you have an air lock not allowing the coolant to flow through the heater core.
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Monday, September 14th, 2020 AT 11:21 AM (Merged)
Tiny
STEVE350
  • MEMBER
  • 1989 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 112,000 MILES
Hi, I recently replaced the intake manifold gaskets on my pick up, it was leaking water into the exhaust and there was little or no heat. The leak is fine maintaining a full radiator, replaced the thermastat at the same time. Still there is no heat. Blower works, cold air. When you switch it from cold to hot you hear the crossover motion but temp stays cold. Appreciate the advice.
Steve
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Monday, September 14th, 2020 AT 11:21 AM (Merged)
Tiny
DE772601
  • MEMBER
Hello well if you still have no heat you have a clogged heater core and to check to see how take both heater hoses off at the fire wall and take a garden hose and spray in the heater core until the water is clear and then repeat the process on the other one. This should clean out the ports so you can get heat again. I hope this will help you.
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Monday, September 14th, 2020 AT 11:21 AM (Merged)
Tiny
CHUCKTODD
  • MEMBER
  • 1989 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
I have changed thermostat and flushed heater core. When motor is hot the heater box is hot but no hot air blows in. Fans blow fine but just room temp air. Any suggestions would be helpful.
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Monday, September 14th, 2020 AT 11:21 AM (Merged)
Tiny
HMAC300
  • EXPERT
One of your actuators isn't working right, check the ones in pic with the double arrow as one will be temperature.
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Monday, September 14th, 2020 AT 11:21 AM (Merged)
Tiny
RAPAULSON
  • MEMBER
  • 1989 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 260,000 MILES
I have checked as the truck warms up, one hose first warms up then the other as the water goes through the core. The blend door operates to change from defrost, windshield, to the floor, heater, but with no heat. Is the blend door also the directional door? How to fix and gain access, even if I can get the door (baffle) to open manually to let the air to blow into the heater core, if that is the problem?
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Monday, September 14th, 2020 AT 11:21 AM (Merged)
Tiny
WRENCHTECH
  • MEMBER
The blend door and the mode door are 2 entirely different components.

If both hoses are hot to the touch, then you likely have a blend door problem.

You should be able to access it by removing the glove box.

https://www.2carpros.com/images/external/57432979.jpg.gif
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Monday, September 14th, 2020 AT 11:21 AM (Merged)

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