Help! No heat

[calhoon]

Got a 2015 3500 with the 6.7 Cummins. searching through this forum I've checked the blend door behind the glove box and it seems to be working. I've reversed flushed and flushed the heater core 4 times. There doesn't seem to be any leaks. I've noticed that the air coming from the vents seems kind of weak. the a/c works fine. Anybody got any ideas.

 

[rzr6-4]

Cabin air filter?

 

[buglao]

Thermostat stuck open.

 

[DudeWalksOnWater]

If you have good airflow, and you are certain that the door actuator is opening to full heat, then you may have have air in your heater core.
You need to bleed it out of the system. Also check if both heater hoses for temperature. If one is hot and the other cool, then the coolant is not flowing. Having said that I have both heater hoses hot, and bled my system, and locked the heater door wide open, and still do not have much for heat. Could be a cheap heater core I put in but ....man what a headache. If you are going to bleed the system, put the front tires up on ramps first. Using a funnel kit connected to where the rad cap goes, will allow you to see the air coming out of the system. Once the engine is warmed all the way up you just keep going until no other bubbles come out. However, if the bubbles never stop coming....that could mean that you have a leaky head gasket and you can get a test kit to check for that as well.