How do you replace heater core in a 2003 dodge ram truck?
If the core appears to be OK, the next concern is with the blend doors that divert air through the heater core. This is a common failure on the RAM. Check heatertreater.net for an explanation of the operation of the system and a fix for the common problems. The RAM has four different DC servo motor controlled air flow doors that are susceptible to failure and all of these need to be checked by either observing the symptoms of failure or reading the codes. The problems are easy to fix with the HeaterTreater kits, but the OEM dealer fix requires removing the plenum box as described above. It is a costly repair if you take it back to the dealer and are not under warranty.
