I have a 2002 ram 1500 that blows warm air,( not hot) from the heater when I accelerate but when I step on the brakes or come to a stop the air turns cold. Any suggestions on what to check. Thank you.

 

what is your temp reading when it happends?

 

My temp reading is normal. The gauge is right in the middle of c-h so I didn't think it would be the thermostat. Someone mentioned to me that it could be the heater core but if it were the core would I still be getting warm air and why would it blow cold when I step on the brakes or come to a stop?

 

Have you checked the coolant level? Also, yes it could be the core being clogged but I would check the coolant level first.

It gets cold when you apply brakes or stop because the engines RPMs is dropping which means the water pump isnt turning as fast. With less coolant and less RPMs, there is less water to be pushed to or through the core.

 

Is there any chance the core could be air-locked?
My work Suburban does this quite often, as the core is well above the water pump.

 

Thanks for the replys guys. I did refill the radiator because the coolant was low but now I have a new problem. When I have the control on vent the driver side blows cold and the passenger side blows warm and when I turn the control on defrost both sides stay cold. I do not have dual controls for driver and passenger, it's just vent, defrost,floor and defrost/floorfor the entire cab. Thanks again.

 

Do a search on here for "blend doors" and you will find a few threads with guys having had that same issue