Question about 2004 Pontiac Grand Am

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I get no heat out of the heater. Coolant level is ok. Thermostat has been replaced recently. Is there a heater control valve to direct hot coolant to the heater core?

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Vaccuum control valve for heater, is stuck or broke. This allows the antifreese to flow through the heater and heat the inside of vehicle. Ccheck vaccuum lines and valve, its by the heater core.
Also, if the antifreese has not been changed, it can clog the heater core not allowing the antifreese to flow. Flush system and check again.

Posted on Dec 12, 2012

  • mlw2720
    mlw2720 Dec 14, 2012

    Not sure how much of the dash I have to remove to get to the valve and core. May have to visit dealer.



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Posted on Jan 02, 2017

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SOURCE: Im getting no heat in my 1999 Pontiac Grand Am, I

Put your heater temperature control in the max position on(this opens the valve for coolant flow through the heater core). Top off the radiator and the coolant resevoir. Make sure the cap is on tight and bring the engine up to operating temperature. Shut off engine, allow to cool, and top off the radiator again. Repeat these steps until you are sure it will not take anymore coolant. Drive the car at speed for 5 or 10 miles and recheck again when cool. It takes awhile to work air out of the system with multiple openings of the thermostat.

Posted on Jan 04, 2010

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SOURCE: heater does not work and car is overheating

Probably a clogged heater core. Orange coolant clots after a while. Should be replaced more often than recommended. If you have intermittent heat you might get lucky with a coolant system flush, otherwise you'll probably have to replace the heater core.

Posted on Dec 14, 2008

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SOURCE: location of heater control valve 2005 grand prix

i don`t think there is a heater control may have an air pocket in system.

Posted on Jan 06, 2009

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SOURCE: 2000 pontiac montana is not blowing hot air.

it seems to be the only thing left would be the heater core replace that and see if that works here to help Shaun

Posted on Nov 16, 2008

james klgr
  • 362 Answers

SOURCE: 2002 montana getting overheated

sounds like a stuck thermostat. but check if the system has a bleeder screw if it does burp it and that will help also.

Posted on Dec 13, 2008

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I changed the thermostat but it still does not heat up what else could be wrong

Heater needs Heater Core, Heater control valve, air diverter inside the car and hot water in the heater core. If you just change the thermostat you must have had a reason. If the car was running hot it could be a radiator clog. If the core is clogged no heat. If the heater core was drained when you changed the Tstat there may be air in it - if so no heat. If the control valve (on the heater hose) does not shift- no heat. If the diverter door in under the dash does not direct the fan air through the heater core- no heat.

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Probability 1) The thermostat is probably stuck open, coolant is not getting hot enough from the engine to provide heat.

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Check operation of the heater coolant on/off control valve and operating mechanism.
Check thermostat is installed and working OK - replace if in doubt.
Check if coolant heater supply hoses are warm/hot when coolant valve on.
If hoses are cold (no coolant flow evident) check coolant system is properly filled (bleed system as necessary to remove possible air locks).
If still no coolant flow check heater system for blockage.
If all above ok, check heater unit air control vanes operation.

Jan 22, 2010 | 2001 Volkswagen Passat

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Would the heater control valve malfunctioning make the engine overheat blowing hot air out the heater one moment,then not blowing the hot air, temp gage spikes 225 plus. The motor takes awhile to heat up...

Heater control valve malfunction will not cause engine to overheat unless coolant is leaking externally...Overheating going down the road can be the result of a few different things...Partly clogged radiator...Insufficient air flow due to possible fan problem...External coolant leak...Make sure fans are operting properly and have cooling system pressure tested for leaks...Gaining and losing heat on the inside of the vehicle usually means system is low on coolant but you must find out where coolant is going

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Why doesn't the heater blow hot air?

If your "Check Engine" or "Service Engine Soon" light is on, you need to have that checked out first.
If not, the next thing you should check is your engine coolant level. (Antifreeze) If the coolant level is low, the engine coolant does not circulate through the heater core and the the heater doesn't work. The coolant level could be low for a number of reasons including a leaky hose, water pump, or head gasket. In any case, if it is found to be low, you need to find out why.
If the coolant level is OK then the thermostat function needs to be checked to make sure that the engine is reaching operating temperature.
If all of the above checks out OK, then the heater control valve and/or the blend air door in the HVAC housing needs to be checked for proper operation. (NOTE: some cars are not equipped with a heater control valve)

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Heater doesn't work. A/C works and air blows, but no heat. Flushed antifreeze and replaced thermostat already. Help.

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