Very little heat

Tiny
TSCOTT0325
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 90,000 MILES
I have changed the thermostat and flushed the system the truck is coming up to temperature okay, still getting very little heat.
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Monday, January 10th, 2011 AT 3:35 PM

29 Replies

Tiny
DR. HAGERTY
  • MEMBER
Was the changing of the thermostat an effort to get the heater "up to speed"? Did you try different settings at the climate controls?
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Monday, January 10th, 2011 AT 3:43 PM
Tiny
TSCOTT0325
  • MEMBER
Yes, turned on off. Nothing seem to work.
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Monday, January 10th, 2011 AT 3:53 PM
Tiny
DR. HAGERTY
  • MEMBER
So the answer to my first question is what? What was the reason for changing the thermostat?
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Monday, January 10th, 2011 AT 4:41 PM
Tiny
TSCOTT0325
  • MEMBER
Mechanic suggested I start there thought maybe it was sticking open.
I live in northern Ohio and the temperatures here have been cold for some time.
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Monday, January 10th, 2011 AT 4:50 PM
Tiny
DR. HAGERTY
  • MEMBER
General Motors strategy for climate controls is to use a blend door to moderate the hot/cold thing. If the heater is not getting hot, then the blend door actuator may be stuck and if so it may require replacement of the actuator or the door or. I will be happy to do some digging to get a clear picture for you, I have a morning appointment right now. Please respond if you have received this so that it shows up in my inbox and so I can be reminded, thanks.
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Monday, January 10th, 2011 AT 5:27 PM
Tiny
TSCOTT0325
  • MEMBER
Received your message and appreciate your help.
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Tuesday, January 11th, 2011 AT 1:00 PM
Tiny
DR. HAGERTY
  • MEMBER
Still looking. Actually I am handing this off to a GM guy, stand by.
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Tuesday, January 11th, 2011 AT 10:54 PM
Tiny
QUINNSDADDY
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • 99,455 MILES
My heater blows cold air at idle, warm air at thirty mph and up. Once it works, it is awesome, but it is like it has a mind of its own. It stays hot when it wants to. But only after I take it on the highway. Water pump or thermostat issue?
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Sunday, April 29th, 2018 AT 4:14 PM (Merged)
Tiny
RIVERMIKERAT
  • MEMBER
Possible water pump or heater core issue. It sounds like the core is not getting sufficient flow.
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Sunday, April 29th, 2018 AT 4:14 PM (Merged)
Tiny
BWEBER72
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 92,000 MILES
My 2500HD's heating/air conditiong has not worked on full blowing power for some time, this morning there is no heat blowing/no defrosters. Any ideas?
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Sunday, April 29th, 2018 AT 4:14 PM (Merged)
Tiny
RHALL77
  • MEMBER
Is the blower motor working at all or is it not switching from defrost to floor and the fan is working?
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+2
Sunday, April 29th, 2018 AT 4:14 PM (Merged)
Tiny
ARBY
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 120,000 MILES
No heat on drivers side, heat on passengers side.
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Sunday, April 29th, 2018 AT 4:14 PM (Merged)
Tiny
MERLIN2021
  • EXPERT
If both heater hoses coming from the heater core are hot, the blend door is not moving, if the inlet hose is hot but outlet is cold, the heater core needs flushing, or replacement. If both hoses are cold, check antifreeze level and thermostat, also rarely but known to happen is the impeller blades on the water pump dissolve over time and may not be pumping enough.
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Sunday, April 29th, 2018 AT 4:14 PM (Merged)
Tiny
ATIMEO
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 49,088 MILES
Heater is only working on passenger side. Blows air on drivers side but no heat.
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Sunday, April 29th, 2018 AT 4:14 PM (Merged)
Tiny
RACEFAN966
  • EXPERT
Okay, it looks like the HVAC control module controls the mode actuator to distribute air flow to the desired vent. If you want to try to fix yourself them let me know and I will get the needed information so you will know where these items are and how to test them one at a time okay. Thanks.
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Sunday, April 29th, 2018 AT 4:14 PM (Merged)
Tiny
GENESISAMON
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 64,000 MILES
When I turn on the heater, I only get cold air on the driver side. The passenger side heat works perfect. The defroster for my windshield also only blows cold air. I have checked all the fuses and tried all the settings for heat and A/C. I have tried to research the problem but I cannot seem to find a solution.
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Sunday, April 29th, 2018 AT 4:14 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Chances are you are dealing with a vacuum leak. The vent doors are actuated by vacuum. Check under the dash for leaks and where the source line goes through the firewall to the engine.

Let me know what you find.
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Sunday, April 29th, 2018 AT 4:14 PM (Merged)
Tiny
SHAUN2448
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • V8
  • AWD
  • AUTOMATIC
  • 62,000 MILES
When I first start my truck and leave it idle with the heater on the heater blows cold air even if it runs for twenty minutes but as soon as I put it in gear it starts blowing hot air.
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Sunday, April 29th, 2018 AT 4:15 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Make sure the coolant is full. Is sounds like there is not enough to make it to the heater core.

Let me know what you find.

Joe
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Sunday, April 29th, 2018 AT 4:15 PM (Merged)
Tiny
POOR123
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • 6.0L
  • V8
  • 4WD
  • AUTOMATIC
  • 100,000 MILES
I have automatic dual digital thermostat with AC in my 'truck listed above (HD) and for about fifteen to twenty minutes it will not blow any heat whatsoever until I nearly arrive at my destination. I have tried tried adjusting the dual temperatures, AC, no AC, floor, face, defrost modes = no heat, and then all of a sudden after fifteen or so minutes of leaving it alone the heat works. On the return trip sometimes it is ten minutes before the heat comes on even when the engine temperature is still warm but sometimes it immediately works fine. What do you suggest is most likely going up?

Thanks
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Sunday, April 29th, 2018 AT 4:15 PM (Merged)

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