heater problem

[bentstroke_02]

Okay when the truck is at a stop the heater will start to blow cold air once i start moving or get rpm up it will blow hot air again. Anyone know?

[04hdfatboy]

Is your coolant low?

[drewactual]

^yup... bet you've got a bubble and need a burp, at best, or have a leaking heater core or somewhere else air is being introduced, at worst.

[bentstroke_02]

Well f i fill it the coolant comes out of cap. I.did a coolant flush last spring. I didnt have this problem tell a few weeks ago

[04hdfatboy]

You have bad head gaskets right? I have seen posts stating that will cause problems with the heater.

[bentstroke_02]

I think i goung to replace either way

[04hdfatboy]

Well you stated above that coolant comes out of the cap so you probably have bad head gaskets.

[bentstroke_02]

Wouldn't temps be weird if it was head gaskets?