Question about 2004 Pontiac Grand Am
Currently blowing cold air from all the vents, can select/change from floor to defroster, etc...both inlet and outlet heater core hoses are hot during normal running temps. The heat/temp selector knob seems to have no effect.
Which engine do you have? 3400 have a bleeder on the water outlet that connects to the upper rad hose. If both are hot I'd say low coolant so air is still in the system (if you rev it may get hot the back off to cold). If not then look into the blend door actuator or the switch controlling it may be bad.
Posted on Nov 12, 2014
Not sure if there is a bleeder valve on these. Not giving a description of what was going on makes it difficult.You may have a plugged heater core. Maybe low coolant. Sometimes it needs to be bled off with a vaccuum drawing the coolant through the heater core. Part of the problem is with these the heater core is higher than the cooling system so the coolant doesnt natrually flow into it, it takes some type of external force to make it go in. I have had luck getting the nose of the car up on car ramps to get the core lower and its naturally started flowing. That is if there is not an obstruction preventing it from doing so.
Posted on Nov 12, 2014
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Posted on Jan 02, 2017
Okay. warm up vehicle, get radiator hoses hot. Turn on heater, fan on low. Grip both rubber heater hoses close to the firewall, from the engine compartment side. They should be too hot to hold for long. If they are not hot, then you have a lack of coolant circulation to the heater hoses. If they are hot then access heater core, behind glove box area. Blend door which moves as you chose HOT or Cold, should be cable controlled, move the controls and be sure the door is actually moving. Keep me posted
Posted on Dec 17, 2008
There is a mix damper inside your duct that controls the heat over heater core and ac evaporator that to your floor and one to your defrost. it is probable an electric actuator, that is not functioning properly. If yu can locate it and manually move it, you might have to remove the actuator motor first, you should be able to figure out your problem, I hope this helps! merry Christmas!
Posted on Dec 22, 2008
SOURCE: i want to flush the heater core
Take off the hoses at the bulkhead/firewall that go to te heater core, use a garden hose and back flush the core by forcing water through the smaller of the 2 hose nipples, if the water runs right through then you have a heater air temp control door actuator problem
Posted on Dec 24, 2008
under the hood on the firewall there is a square boxlike cover beside the maxifuse&relay. there is a vacucum hose there that controls the vent shutoff had same problem with my 93 bonneville sse when purchased, check to see it has no cracks or has pulled out of rubber connecter .
Posted on Mar 28, 2009
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