Heater not working properly

HANK SCHEELK

MEMBER
2006 PONTIAC MONTANA
2.3L
V6
2WD
AUTOMATIC
120,000 MILES

No heat, or heat for a little while, then no heat. It has a front and back heater core. Thermostat is not sticking. Vehicle runs at normal operating temperature. Bleed system for possible air in the system. Water pump is working normally.

Should I flush the coolant system, before taking on the blender door actuator, and possibly the door itself jammed, or may had an obstruction that keeps it from moving freely.

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

If the heat seems to come and go, this sounds more like a heater core issue than the blend door.

However, if the entire system is not operating then that sounds like a control issue.

Here is a guide that will help with this issue:

https://youtu.be/SNRb6pSwYuU

Let's clarify if the front and rear heat are coming and going at the same time or not.

I would suggest checking the coolant level and flushing it if it looks like because you could have an air pocket if this is just the front or rear system.

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

The next thing I would suggest is let's check the temperature of the heater core lines and make sure they are the approximate same temperature when this issue is happening and that will tell us if the heater core is restricted.

https://www.2carpros.com/articles/how-to-use-an-infrared-temperature-meter

Let's start with this and go from there.

Thanks