Heater blowing cold air

Tiny
DUMMKOPF352
  • 2005 CHEVROLET UPLANDER
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 35,000 MILES

My sister's car. Antifreeze looks decent, blower motor works, but no heat. Problem may have developed suddenly or over 2.3 weeks gradually, not sure. Acts like plugged heater core or valve in coolant line not opening. Are heater hoses easy to touch, to feel temperature? If so, where? Anything else to be checked? Is valve electric or vacuum actuated? My sister has bad arthritis and must rely on others.

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Sunday, January 16th, 2011 AT 1:48 PM

10 Replies

Tiny
WRENCHTECH
  • EXPERT
  • 20,808 POSTS

With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If not too hot to hold, then you have to look at the actual engine temp and if that is up, if it is, then your looking at a restricted heater core.
If you find that they are both too hot to hold, then the heat in that vehicle is controlled by a blend door that regulates heated air flow. It is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged. This is what needs to be determined by examining the actuator and see if it is responding to heat change commands or not.
If they are both not too hot to hold on to, then you either have a restricted heater core or the system is not completely full and getting air pockets for some reason.

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Sunday, January 16th, 2011 AT 1:49 PM
Tiny
DUMMKOPF352
  • MEMBER

Thanks, very helpful. Hoses near firewall feel about same temp as upper radiator hose. Owners pamphlet says one fuse block (of 2) is on passenger side under instrument panel. Cannot find looking under glove compartment. Ditto on RH side above accel pedal. Is the "instrument panel" something other than the dashboard?

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Tuesday, January 18th, 2011 AT 2:20 PM
Tiny
WRENCHTECH
  • EXPERT
  • 20,808 POSTS

No, instrument panel and dash are the same thing. It sounds like you're having a problem with the blend door operation.

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Tuesday, January 18th, 2011 AT 3:23 PM
Tiny
SURFCITY
  • MEMBER

The 1st fuse box is on the very end of the passenger side instrument panel, you have to fully open the door to get at it. The 2nd is under the hood on the passneger side in the black bos that has the jumper peg sticking out.

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Wednesday, February 16th, 2011 AT 7:55 PM
Tiny
DUMMKOPF352
  • MEMBER

Thanks. The 1st sounds like the way Generous Motors located a fusebox on my Chev 2002 Silverado 2500HD (except maybe for right vs left). Appreciate your help!

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Thursday, February 17th, 2011 AT 8:08 PM
Tiny
DEBJOROB
  • 2008 CHEVROLET UPLANDER

Heater problem
2008 Chevy Uplander 6 cyl Front Wheel Drive Automatic 55000 miles

Heater blows cold air when idling but heats up when accelerating.

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Wednesday, December 14th, 2016 AT 5:00 PM (Merged)
Tiny
EAGLEMAN12
  • 2006 CHEVROLET UPLANDER
  • 3.5L
  • V6
  • FWD
  • AUTOMATIC
  • 155,000 MILES

The engine warms up normally, coolant level is ok, but the air from the heater is cold.
I do not know what to check, or how much it might cost to have it repaired.

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Wednesday, December 14th, 2016 AT 5:00 PM (Merged)
Tiny
JOHNNYT73
  • EXPERT
  • 944 POSTS

Mostly this happens on GM cars with air in the system. Do you have heat when you raise the RPM to about 3000-3500?

When engine is cool. Remove radiator cap, loosen the coolant bleeder screws, start engine and let reach operating temperature, turn on the heat, begin raising the RPM to 3000 and hold for about 4 seconds (do by hand on the throttle body if cable actuated so you watch the bleeder screws), be sure to keep the coolant level up in the radiator, keep the bleeder screws open till you get good solid flow of coolant then tighten them shut, once the all the air seems to be out of the system, confirm you have heat at idle, then turn of the engine, when engine has cooled completely, check coolant level at the radiator and top off as needed.

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Wednesday, December 14th, 2016 AT 5:00 PM (Merged)
Tiny
EAGLEMAN12
  • MEMBER

Could you please tell me where the bleeder screws are?

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Wednesday, December 14th, 2016 AT 5:00 PM (Merged)
Tiny
JOHNNYT73
  • EXPERT
  • 944 POSTS

If you have an engine cover go ahead and remove it (may need to remove the oil cap and tube). Somewhere along the top/front of the engine you will see some 8mm screws that screw into a 10mm screw. You loosen only the 8mm head (if possible. Sometimes you have to loosen the 10mm if the 8mm is stuck). I will attach a photo of what they look like.

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Wednesday, December 14th, 2016 AT 5:00 PM (Merged)

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