Thread: '98 GTP with dual climate control no heat on driver/ luke warm on passenger

My 1998 GTP has no heat on driver's side even when setting LED to 90 degrees; set passenger to 90 degrees and some warm air comes out of the vent. Both heater hoses going to the heater core are hot at operating temperature; however I flushed the heater core.

It only takes a few minutes to go from nothing to running at 230+ degrees F, but no heat. Low coolant light on, so I added coolant to overflow reservoir. I opened the radiator cap and started the vehicle adding one gallon of anti-freeze/coolant when it was running. Replaced cap and let it warm to 220+ degrees F, no heat.

Nothing that I have done has changed the fact that no heat is available. Today was record high of 65 degrees F but tomorrow it is forecasted as 35 degrees F for high and 20 degrees F for low.

Please help!

How do I make sure the blender doors are moving to allow the heat to enter the cabin?

How do I make sure the middle vacuum line on top of the supercharger tree isn't broken anywhere as it enters the cabin?

How do I bleed the cooling system from the thermostat housing screw to make sure no air is trapped up high?

coolant bleeding- http://www.grandprixforums.net/threa...coolant-system

Also, why was the low coolant light on? You either have an external leak somewhere or the LIM gaskets may be bad letting the motor slowly eat it, which if this is the case you need to fix it asap before you spin bearings and look for a used motor. Have the LIM gaskets ever been changed on it?

I believe that LIM indicates a "lower intake manifold" gasket???? If so, no I have never torn into the motor to replace gaskets. I have not seen anything unusual when changing oil that would indicate an internal leak of coolant that would degrade the viscosity of the synthetic oil that I use. In other forum posts I have read that the idiot light for low coolant was generally a sensor which commonly failed on 1997-2003 Grand Prix models.

I have never seen puddles of coolant or anything else that signals an external leak. Is there any other way of testing before I tear into the motor?

Originally Posted by FordMan77

coolant bleeding- http://www.grandprixforums.net/threa...coolant-system

Thanks for the link to the bleeder control. It seems pretty simple.

All things point to the blender door actuator on the driver's side which appears to be a b%@!^ to get too if you have the hands of an American male over the age of 12 years. I am concerned about the low coolant level especially if it is leaking into the motor oil. I guess that I will have to park it until the weather changes and then tackle this mess when we thaw.

Thanks, that way I can "test" before replacing.

Any ideas on the low coolant level?

Thanks, all good ideas. I was suspecting that the overflow reservoir was a possibility but I have never seen any puddles underneath the vehicle. I am praying for an "easy" fix so that I do not have to tear into the motor. I'll update the thread after testing this weekend.