knuckleheaf27
New member
I have a 2001 Sierra 1500. My problem is the heat gets warm but not hot. When i turn the heat off for a moment and then turn it back on it blows hot for just a few seconds before going warm again. I've checked all the basics, thermostat is fine, coolant is good, and the heatercore has no leaks. I was told to flush the heatercore with mineral spirits to rid it of any build up of gunk. Has anyone had the same problem? Thanks for any input....