That's an indication that the heater core is plugged up. Someone may have added sealer to the system at one time or left Dexcool in there for too long,
I would remove the 2 heater hoses and use a garden hose to flush the core in both directions and see if that helps.
Also make sure you have sufficient coolant and the core didn't just freeze.
Tuesday, November 18th, 2014 AT 3:40 AM