Hello. Please include all the details about your issue so I can accurately advise you. I cannot see your vehicle so please be detailed.Are the heater hoses to the heater core hot when you touch them?Customer :i have no heat, changed the t statblows cold airGM Tech (Cam) :OK so we need to see first if there is hot water getting into the heater core or not so we need to see if the heater hoses, both are hot.Customer :one hose is hotGM Tech (Cam) :and the other?Customer :warm to the touchGM Tech (Cam) :but significantly colder?Customer :yes... are these cars know for the heater core to plug upGM Tech (Cam) :Ok, easy place to try next, take those lines off the heater core and spray water from a pressure washer into the port that was the colder line first. Flush both ways and see what that does.This will clear a blockage and the high pressure creates enough turbulence to get the coating off the inside of the heater core from the coolant.Customer :will try that, are these cars known for the heater core plugging upGM Tech (Cam) :yes they are.Customer :so i should put a new one inGM Tech (Cam) :No, try flushing first, much cheaper!!!!Customer :with new coolantGM Tech (Cam) :IF it works then do a whole coolant flush.Customer :ok will try thatGM Tech (Cam) :If that does not help then we could be looking at the actuators that move the heater doors.Customer :but that don't stop the coolant flow?GM Tech (Cam) :The actuators stop the air flow through the core, not coolant flow.Customer :will try the flush first cause one hose is coldGM Tech (Cam) :That is the logical place to start.Customer :if not i will be backGM Tech (Cam) :Absolutely!!Customer :thanks for the infoGM Tech (Cam) :MY pleasure.