Chevrolet Repair: Cooling system, coolant level, heater core

Question
Hi Van

Trying to find out why my heater is not working on my Chev Blaze 1998 import.  Thermostate tested and working fine.

Cheers
Gerri

Answer
Hello Gerri,
It is possible the heater core is plugged up, or the coolant level is just too low, but the most likely possibility is the connection on the rear of the intake manifold, where the heater hose connects, is stopped up.
There seems to be a little orifice there, and they will plug up, and no coolant flow through the heater core.

Careful though when messing with it. They are a quick connect, and made of aluminum, and will break off easily.
There is a replacement fitting that uses a regular hose and clamp, and that will fix it right up, but it may take some work to get the old one out if it breaks off in the manifold.

Some models have returned to having a coolant control valve above the heater core. I don't know if yours has that or not, but if it isn't opening, that would also cause no heat.

Van