My 99 GMC has always had a great heater until recently. It started taking longer to heat up abouta month ago. Over the last couple of days it will not get warm at all. Blows cool air. Does this sound like the heater core? How much to repair?

Thanks,
Marty

 

well whats your coolent guage doing? if your coolent isnt getting hot sounds like a simple stuck open thermostat, if your low on coolent or you see a nice puddle on your floor, then its a core.

 

I have had to add coolent, but have not seen any on the floor. Temp gauge seams to be working.

Marty

 

then i would say its the core. if your low on fluid and the truck seems to be heating up to operating temp, probally the core

 

did ya get it full?..it'll be cold if its low