The last couple weeks I have not had heat in my 1998 GMC Jimmy. It just blows out cold air. The temp gauge reads that the car is warm (normal reading). The air conditioning does not work either, but that has been in and out for a couple years. The heat however is a new problem however. Someone suggested that my heater core is plugged up?? Is that possible? Another suggested it was the switch (warm-cold), but on a warm day if I turn the heat on, warm air comes out and if I switch it to cool, cold air come out. And I already checked the antifreeze and that was fine. Any suggestions would be appreciated.

Corey

 

Id say the heater core is quite likely. They may be able to power flush it if you are lucky. Otherwise replace the core.

 

Flush the cooling system and then flush the heater core by itself by removing the hoses at the engine and spray water through both ways until clear.Reinstall the hoses,fill it with coolant and you should have heat.

 

I have the same problem but I am still unable to find an answer for this problem. Is this web site a place to help us solve our problems or just a place to share them?

 

could also be a problem with the air blend door, feel the hoses to the heater if both are hot then the problem is a blend door, or the actual controls for the heat.

if we're not supposed to eat animals why are they made out of meat?

 

Adding to what Speedwrench said, if one of the heater hoses is cooler than the other then the heater core is plugged.