Hello. My 2000 4x4Jimmy has no heat. Fan blows good. I checked coolant level-ok. Both lines in and out of heater core are Ice cold?? Now what?

Thanks,
John

 

is the heater core clogged?? pull off the hoses and flush it out.

 

Have you done anything with the cooling system lately?
It sounds like the coolant is low because you should be getting heat to at least the inlet hose of the heater core.
Remove the heater hose from the heater core and see if there is any coolant in there.
It sounds like you have an air lock in the system.

 

A simple check is to remove the thermostat. This will allow heated coolant to free flow through the engine and heater core. If after removing the thermostat, the lines to the heater core get hot (with engine temp up) then replace thermo with a new one. If one line into heater core gets hot, but the other is not, then the heater core is plugged. You can reverse flush the core with a garden hose and some misc fittings to make a hose rig to attach to the core, or you can disconnect the line back to the engine and reverse flush from there.

Some other things to check: does your coolant level drop occassionally? If so, check your oil. Is it chocolate milky? If so, you have a leaking intake manifold gasket which should be replaced immediately. With engine cold, is the coolant level low? If your IMG's are not leaking, park the vehicle with the front end raised (radiator at high point), start engine, slowly fill radiator with 50/50 coolant mix to drive out (burp) any air trapped in system. Good Luck.