Heater not working?

Tiny
DKVOGEL
  • MEMBER
  • 1999 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 242,000 MILES
Heater not working. Replaced the thermostat heat still not working.
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Sunday, December 5th, 2010 AT 11:21 PM

31 Replies

Tiny
2CEXPT
  • EXPERT
It sound like the temperature blend door actuator is not working here are two guides to help us fix the problem

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

and

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

Please run down these guides and report back.
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Sunday, December 5th, 2010 AT 11:38 PM
Tiny
VVP45883
  • MEMBER
  • 1999 CHEVROLET SILVERADO
Heater problem
1999 Chevy Silverado Two Wheel Drive Automatic

Have replaced thermostat, still no heat is there a valve somewhere that need to be replaced?
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Monday, September 14th, 2020 AT 11:10 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi:
If the truck has a heater control valve, it would be on one of the heater core hoses. However, I don't think it does. Let me know if you find one.

Joe
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Monday, September 14th, 2020 AT 11:10 AM (Merged)
Tiny
RUSTY SMITH
  • MEMBER
  • 1999 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • AUTOMATIC
  • 20,000 MILES
Heater not blowing hot air.
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Monday, September 14th, 2020 AT 11:10 AM (Merged)
Tiny
SATURNTECH9
  • MEMBER
Is it a dual climate control?if so are both sides not getting hot?

These guides will help us fix it

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

and

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

Please run down these guides and report back.
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Monday, September 14th, 2020 AT 11:10 AM (Merged)
Tiny
SATURNTECH9
  • MEMBER
Is it the left side not getting hot?Usually the left blend door actuators go out on those trucks.
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-1
Monday, September 14th, 2020 AT 11:10 AM (Merged)
Tiny
GGWOLVERINE1
  • MEMBER
  • 1999 CHEVROLET SILVERADO
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 135,000 MILES
The problem that I have is when I have the heater or defroster on hot I get nothing but cool air. The hoses going to heater core are both hot. I m not a mechanic so any advice would be greatly appreciated. Thank you.G
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Monday, September 14th, 2020 AT 11:10 AM (Merged)
Tiny
BMRFIXIT
  • EXPERT
Most likely to be a blend door actuator issue. If the thermostat is opening properly and heater core not clogged-up -could be one of the following: Heater control valve, air mix/blend/mode/recirculation door problems, vacuum and actuators to include the HVAC control module
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Monday, September 14th, 2020 AT 11:10 AM (Merged)
Tiny
CNJHART
  • MEMBER
  • 1997 CHEVROLET SILVERADO
Heater problem V8 Four Wheel Drive Automatic 223000 miles

i replaced my t-stat and fan clutch and I still have no heat what should I do?
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Monday, September 14th, 2020 AT 11:10 AM (Merged)
Tiny
JDL
  • EXPERT
Hi, does the engine reach operating temp? Are the heater hoses hot? Maybe the heater core needs to be flushed?
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Monday, September 14th, 2020 AT 11:10 AM (Merged)
Tiny
ALASKADOC
  • MEMBER
Where do I check the heater hoses? If heater core needs flushing, where is the heater core in my 1994 Chevy Silverado z71?
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Monday, September 14th, 2020 AT 11:10 AM (Merged)
Tiny
KEN
  • ADMIN
Hey,

You check the heater hoses up by the fire wall with the engine warm. Check your coolant level engine cold. To me though it sounds like you have a temperature blend door actuator that is out which is common. Here is a guide to help us fix your truck which is one of my favorites vehicles btw.

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

and

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

Check out the diagram (Below)

Let us know what happens and please upload pictures or videos of the problem.

Cheers, Ken
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Monday, September 14th, 2020 AT 11:10 AM (Merged)
Tiny
GEORGE CRAWFORD
  • MEMBER
  • 1997 CHEVROLET SILVERADO
  • 22,200 MILES
No interior cab heat. Position control switch does not activate all functions. Changed thermostat in engine. Line to heater core hot no heat or warmth in return line. Also the high speed setting does not work.

Last year the fan motor quite. Replaced but the high speed position on the switch does not work. Now there is no heat coming into the cab. The blower works up to the 3rd setting but I am unable to get the function switch to change position of where the air comes out to do more than 2 settings.
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Monday, September 14th, 2020 AT 11:11 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Make sure coolant is full. With engine hot and heater on, make sure both heater core hoses are hot. If only one is, flush the heater core. If both are hot, check blend air door near the heater core. It is responsible for allowing heat to enter the vehicle.
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Monday, September 14th, 2020 AT 11:11 AM (Merged)
Tiny
CHEVYZ
  • MEMBER
  • 1997 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 17,100 MILES
Temp doesn't ever get above 150. When it's below 20 degrees and cold, water temp is around 120-130. Cab Heat is warm at best. The thermostat is new and functioning properly. I have 2/3 of the radiator facing covered with cardboard. The cap is cold after 20 minutes of x-way driving. Do you have any ideas.
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Monday, September 14th, 2020 AT 11:11 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
If the temp never heats, it has to be the thermostat. If it is closed, very little coolant circulates which causes the engine to heat up. When hot, then it opens and allows the coolant to flow and cool the engine. How have you checked the t-stat? Here is a how to if you want to try it.

https://www.2carpros.com/dia/test_thermostat.htm

Check it and let me know what you find.

Joe
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Monday, September 14th, 2020 AT 11:11 AM (Merged)
Tiny
DJROSE43
  • MEMBER
  • 1997 CHEVROLET SILVERADO
  • 5.6L
  • V8
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
I changed intake gasket and heater hasn't worked since.
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Monday, September 14th, 2020 AT 11:11 AM (Merged)
Tiny
JDL
  • EXPERT
Just a few questions. Does the engine reach normal temp? Are the heater hoses hot? Does the blower motor work? Is there circulation through the heater core?
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Monday, September 14th, 2020 AT 11:11 AM (Merged)
Tiny
PEASE350
  • MEMBER
  • 1997 CHEVROLET SILVERADO
  • 30,000 MILES
Intermitent problem, Temp gauge barries 260 and engine doesn't feel heat can touch the engine block, replaced the thermostat and water pumped and gravity blead the air out of the system. Can start the truck up and let it warm to temp and heats awsome go a half mile down the road and the gauge barries and blows cold air, after another half mile I assume the thermostat opens and temp gauge reads normal and heat blows fine for rest of day.
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Monday, September 14th, 2020 AT 11:17 AM (Merged)
Tiny
HMAC300
  • EXPERT
Make sure your coolant level is at right level first. Then get where the truck overheats. If you have elecetric fans disconnec them or pull the relay so they won't start. Then touch all around radiator and feel for cold spots or loose fins. If you feel any cold spots, the rad is bad an dneeds replacing or recoring. It should be the same temp all over rad.
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Monday, September 14th, 2020 AT 11:18 AM (Merged)

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