2007 Silverado 2500 No heat

[Will Hayes]

I own a 2007 silverado 2500 (new style) has a 6.0L gas engine.

 

  I'm having trouble with the heat. It gets warm but never hot like it should be.

I have flushed the coolant and the core 3 times, changed the blend door actuator and the thermostat.

 

  I can hear the actuator turning as I adjust the climate knob till about 1/2way onto the hot side then the motor seems to stop making a noise. (I suspect something maybe be blocking the actuator inside the vents?)

 

  When the air is in recirculation setting it warms up rapidly (1min or so) and works as it should. When changed back to outdoor air it cools back down.

Not sure where to go from here, any help would be appreciated thank you!

[richard wysong]

are the heater hoses about the same temp? if so the core is clear and it is probably a blend door issue, if 1 is cooler than the other the core still has a blockage and if reverse flushing it doesn't clear it it will need to be replaced. It is also possible to have a blockage on the engine side of the heater hoses

Edited January 26 by richard wysong

[Will Hayes]

1 minute ago, richard wysong said:

are the heater hoses about the same temp? if so the core is clear and it is probably a blend door issue, if 1 is cooler than the other the core still has a blockage and if reverse flushing it doesn't clear it it will need to be replaced

Yes both hoses are the same temperature. (Has been flushed for good measure 3 times)

The blend door actuator has been changed and the issue still persists.

[richard wysong]

 Could be debris in the box preventing it from closing off the evaporator. Unfortunately there is no easy way to clean it out. Maybe a borescope will help you determine whats going on

[Will Hayes]

1 minute ago, richard wysong said:

 Could be debris in the box preventing it from closing off the evaporator. Unfortunately there is no easy way to clean it out. Maybe a borescope will help you determine whats going on

Will give the borescope a try. Thanks for the reply.

[davester]

If you remove the actuator, you can manually rotate the post for the door and see how it feels when you move it to it's limits.

[Will Hayes]

7 hours ago, davester said:

If you remove the actuator, you can manually rotate the post for the door and see how it feels when you move it to it's limits.

 Yes I have, it "feels" fine but is difficult to tell.

 When I turn it to the max there isn't any difference in heat. Remains the same Luke warm temperature.

[davester]

If you manually force the door to each extreme, and the air is cool one way, and only warm the other way, when the engine is hot, that points towards the heater core not doing a good job, either because the interior of the core is plugged, or the fins are.

[Will Hayes]

On 1/26/2024 at 10:02 PM, davester said:

If you manually force the door to each extreme, and the air is cool one way, and only warm the other way, when the engine is hot, that points towards the heater core not doing a good job, either because the interior of the core is plugged, or the fins are.

I've flushed 3 times till water was clear, both hoses are the same temperature going into the heater core.

Thanks for the help

[davester]

It could still be partially plugged, so you aren't getting full flow through the heater core.

[Will Hayes]

Sounds like I will have to change the heater core. Thanks

[asilverblazer]

1 hour ago, Will Hayes said:

Sounds like I will have to change the heater core. Thanks

In either case, a more thorough inspection inside.

 

If it gets nice and hot on the recirculation setting, then cools off when switching back to allow outside air in - I would try to watch the door movements to confirm they are doing what they should.

 

Seems like I remember something about the actuators needing the limits programmed too, but I don't recall the specifics...