Originally posted by Big Jim:
When the water pump fails, the heater will NOT blow hot.

Check for a stuck shut thermostat.


Thermostat would be the first to check, but don't rule out the water pump. When our old Buick's water pump failed, the heater was still working. Yes, coolant is what runs through the heater, but there IS still coolant flowing through the heater core when the water pump fails. It's just not enough to cool the car, but if the day is hot enough, and the coolant is already hot, the heater can indeed blow warm.

He could have a blockage in a hose for all we know...but I still believe that the heater can still work in the case of a bad water pump. And if the thermo-stat was bad, wouldn't coolant not flow through the heater either? To check the thermostat, just feel the heat of the hoses before and after it. If one is cold and one is not, there is your problem.

2000 Contour SE