[pronova]

I have a 03 Duramax, the problem is that the heater won't always blow hot and when it does is seems at low rpm it blows cool again. I replaced the thermostats and bleww out the heater coil. But still some times it works but most of the time it doesn't. Little too cold not to know if the heat will work or not. What's my next move??
Thanks

 

[ChevyDMax89]

Bad heater core... are you smelling or seeing anti-freeze?

 

[BUBBA3M]

X2 what he said ^^^^^^^^^^^^^^^^

 

[pronova]

Not so far..

HAven't smelled or seen a drop of antifreeze...

 

[DuramaxSMOKE11]

check your radiator and see if its plugs. put your hand on the inlet and outlet hoses and see if they are both hot and also the same of the heater core

 

[pronova]

The hoses all finally get got but it takes a while, could the radiater be clogged? How long should it take for the truck to hit 210 in the 25-30 degree weather? Should I try some radiater flush/sealer? Sucks driven the mini van everywhere...

 

[jmaz268]

The hoses all finally get got but it takes a while, could the radiater be clogged? How long should it take for the truck to hit 210 in the 25-30 degree weather? Should I try some radiater flush/sealer? Sucks driven the mini van everywhere...

in 25-30 degree weather mine rarely does hit normal operating temp unless I'm towing something. Even at highway speeds it doesn't usually sits at around 160-170