On my 03 ram when I first turn the heater on it blows hot for a few seconds but then it blows cold. Does anyone know what could be the cause of this? Any help is appreciated.

 

check your coolant level... then top it off! It sounds like your just low on coolant.

SPEED SAFE, AIR RAM

 

checked coolant level and it is good, any other ideas?

 

Heater core plugged maybe??

 

How about a blend-door malfunction! If the stepper motor or heater temperature control switch malfunction, the door that covers the heater core might only open for a short time and then close. When clsoed, no heat. Just a thought. There are dianostic procedures in the online version of the service manual. I've seen the 05 manual and suspect that the heater mechanism is no different for the 03s.

Roger...

 

Ok I had the core flushed didnt help the driver side but I am getting heat out of the passenger side vents now. Any other ideas guys??????

 

I'm having a similar problem on my 03. It will blow hot when I'm moving or the RPM's are up, butwhen I sit at a stop sign/light it starts to blow cold. This only happens when it's warming up, after a while it's fine.