My heater does not work?

Tiny
KYLEMILHAUPT
  • MEMBER
  • 2007 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 2WD
  • AUTOMATIC
  • 123,456 MILES
Started out the heat wasn't functioning so well. Engine started to run hot, but wasn't overheating. This all over 2 days turned to warning lights for hot engine/overheating and no hot air from the blower. Still blows cold though. I'm mechanically inclined enough to switch out a pump or heat sensor or thermostat and what not. I just could use sure fire direction in how to better assess the problem. I'm disabled and have a limited income, so if I could replace the one thing that's wrong and not just run on down the line. I have only 1 vehicle too and live in the boonies, help. Any advice to a novice on how to do a flush, without a fully stocked shop? Like with a garden hose.
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Thursday, February 13th, 2020 AT 12:18 PM

37 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

What you described sounds like the coolant level is low. Have you checked it? If it is full, the first thing I would suggest is flush the system and replace the thermostat.

Let me know. As far as a flush, here is a link explaining how it is done:

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

THis guide will help us fix the heater operation

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

Please run down these guides and report back.
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Thursday, February 13th, 2020 AT 6:05 PM
Tiny
MACLAUSEN
  • MEMBER
  • 2006 CHEVROLET SILVERADO
  • 6.0L
  • V8
  • 4WD
  • AUTOMATIC
  • 180,000 MILES
Blower working fine. Controls to select floor, dash, or defroster working fine.

Used to blow hot air, then occasionally would go to cold air until the truck was re-started. Then, while blowing hot air, I adjusted temperature sliders a bit and all hot air went away, cold air only.

HVAC control module or mode door actuator? (Probably the control module).

Thoughts?

Additional information: Work truck with driver/passenger side temperature selection. Cold air blows from both sides regardless of settings.
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Saturday, September 12th, 2020 AT 10:09 AM (Merged)
Tiny
PATENTED_REPAIR_PRO
  • EXPERT
If it's electrical there is most likely a trouble code stored in the module that will point you in the correct direction. Have the trouble codes retrieved.
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Saturday, September 12th, 2020 AT 10:09 AM (Merged)
Tiny
LAXWARRIOR
  • MEMBER
  • 2006 CHEVROLET SILVERADO
  • 60,000 MILES
The heater only blows cold air. The line into the firewall is hot, but the line out is cold. Is this an actuator problem or a dirty heater core? How do you clean the heater core? Before it only blew cold air, it used to blow hot then slowly drop to cold not it is just cold.
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Saturday, September 12th, 2020 AT 10:09 AM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
It sounds like a clogged core. Remove both hoses and flush with a garden hose. Do it in both directions several times. If that does not do it, it may have to be replaced.

Roy
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Saturday, September 12th, 2020 AT 10:09 AM (Merged)
Tiny
BOBBYG187
  • MEMBER
  • 2006 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 53,000 MILES
My air conditioner and heater decided they both dont want to work they worked yesterday morning then yesterday afternoon get in my truck to go to work and they dont work
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Saturday, September 12th, 2020 AT 10:09 AM (Merged)
Tiny
2CEXPT
  • MEMBER
Check and test the HVAC/ECAS fuse 10amp and the blower fuse 40amp in the underhoos fuse block if okay have the HVAC control module and blower control processor checked out
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Saturday, September 12th, 2020 AT 10:09 AM (Merged)
Tiny
PATRICIA BUTLER
  • MEMBER
  • 2005 CHEVROLET SILVERADO
  • 70,000 MILES
Hi, thank you for your time.I recently noticed this problem with the cooler weather setting in. It doesnt happen every time I use the heater, however it has happened on two recent occasions weeks apart. Thermostat reads around 240 but Im only getting outside air temp even with heat all the way up. Both times this has occured, the heat eventually came on as I was driving for some time, maybe 5 miles or so. Ive also noticed a slight smell of antifreeze after arriving to my destination. This isnt coming into the vehicle thru the vents, but when I get out of the truck, I can smell it. Again, thank you for your time. Hopefully this wont cost alot to fix.
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Saturday, September 12th, 2020 AT 10:09 AM (Merged)
Tiny
2CEXPT
  • MEMBER
If you're smelling coolant outside the vehicle its leaking somewhere could be at the Rad cap or reservoir. Is the engine overheating?Check the thermostat and the air blend door/actuator-start here
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Saturday, September 12th, 2020 AT 10:09 AM (Merged)
Tiny
05CHEVY
  • MEMBER
  • 2005 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 102,000 MILES
2005 Silverado - A month ago there was no heat. Brought it to the dealer and they "fixed" it (low coolant, leaky pump). Now, I only get heat while driving. While the fan continues to work, the temp of the air gets much cooler. Example: drive down highway, its fine except when sitting intraffic, then it gets cold. Start going again, and it's fine.
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Saturday, September 12th, 2020 AT 10:10 AM (Merged)
Tiny
DOCFIXIT
  • EXPERT
Was thermostat replaced?
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+2
Saturday, September 12th, 2020 AT 10:10 AM (Merged)
Tiny
05CHEVY
  • MEMBER
Not that I am aware of. Does this sound like a thermostat issue?
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Saturday, September 12th, 2020 AT 10:10 AM (Merged)
Tiny
DOCFIXIT
  • EXPERT
Yes once moving coolant gets cooled without thermostat closing to keep coolant temp up it will cool down
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Saturday, September 12th, 2020 AT 10:10 AM (Merged)
Tiny
05CHEVY
  • MEMBER
Ironically, around the same time, the drivers side heated seat started to malfunction. It turns on, the lightS on the door panel go on, however after about 30 seconds or so it automatically shuts off and the lights go out. The passenger side works fine, unless the drivers side is turned on. When the drivers side suts off, it also shuts off the passenger side when it goes out so they both go out at the same time. Thoughts?
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Saturday, September 12th, 2020 AT 10:10 AM (Merged)
Tiny
LONGSACKET143
  • MEMBER
  • 2005 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 53,000 MILES
My chevy truck started overheating and the heater quit working. The mechanic said no water was being circulated. Is there a switch or something or is it a water pump.
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Saturday, September 12th, 2020 AT 10:10 AM (Merged)
Tiny
CHARTAN
  • MEMBER
Here's 2 thoughts.

Is the thermostat ok?

Is there possibly a coolant leak? You need to check the coolant in the radiator, not the bottle.

There's no switch, so could be the water pump if the above issues are ok. Check the hole in the bottom of the water pump to see if it is leaking.
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Saturday, September 12th, 2020 AT 10:10 AM (Merged)
Tiny
KGREENE
  • MEMBER
  • 2005 CHEVROLET SILVERADO
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 130,000 MILES
Driver side blows cold air while passenger side blows hot air when heat is on. I changed the blend door actuator for driver side still blows cold air. I even moved flap for blend door by hand to see if changing the position would make hot air come from driver side vents. But it did not. Still blows cold air I am at a loss for what it could be.
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Saturday, September 12th, 2020 AT 10:12 AM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Good morning.

Are both heater hoses hot under the hood going into the truck?

It sounds like the heater core is either low in coolant or it is partially clogged.

You can try to flush it yourself by removing both hoses and use a garden hose to run into each side. Run it back and forth until all debris is gone and you have a good flow from both sides.

Beyond that, you may need a heater core.

Roy

https://www.2carpros.com/articles/car-heater-not-working
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Saturday, September 12th, 2020 AT 10:12 AM (Merged)
Tiny
KGREENE
  • MEMBER
Okay, so I flushed core like you said from both sides small amount of debris cam out but not a lot to plug it. Still the heat only works on passenger side. I turned A/C on and only cold air came from passenger side. Is there some sensor in there that could be bad why it only blows fan air on driver side?
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Saturday, September 12th, 2020 AT 10:12 AM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Nope, no sensor. You said you moved the door manually and no heat. That leaves only the heater core.

Roy

Heater/Vent Module Replacement

Removal Procedure

1. Drain the engine coolant. Refer to Cooling System Draining and Filling See: Cooling System > Removal and Replacement.
2. If equipped remove the auxiliary battery.
3. Reposition the inlet heater hose clamp from the heater core.
4. Remove the inlet heater hose from the heater core.
5. Reposition the outlet heater hose clamp from the heater core.
6. Remove the outlet heater hose from the heater core.
7. Remove the I/P carrier. Refer to Instrument Panel Carrier Replacement See: Dashboard / Instrument Panel > Removal and Replacement.
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Saturday, September 12th, 2020 AT 10:12 AM (Merged)

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