'97 1500, 5.2. Anemic heat. The air direction control works, the temp control **** is operating, the blower fan responds to the fan speed control. The temp gauge gets to 195 on a cold day in under 10 minutes and the engine maintains 195 under all driving conditions. I've opened the heater hoses both on the passenger side at that connector in the hose and disconnected the driver's side hose at the water pump. I put full strength flush additive into the heater core and ran water under pressure through the heater core finishing up with a burping of the heater core process to ensure that there was not air trapped in it as best I could. Both input and output hoses to the heater core get quite hot when the engine is running. Does anyone have any experience with the air flow through the heater core getting restricted/clogged with debris or an internal component breaking and making the air flow through the core a problem? The temp control on the dash does seem to be working and when I rotate it fully clockwise I can hear what sounds similar to a plastic door reaching its limit (small thunk).

 

Need a new core.

 

If your truck has A/C, you can't see the heater core without pulling the dash, and heater box. You can see the evap core if you pull the blower motor. (and yes, it does tend to collect stuff there.... certainly worth looking at.)

On my 96, I disconnected the "in" line at the metal coupler in the middle of the hose, and pulled the return line off the metal pipe at the water pump, plugged the engine side off, so I didn't lose much coolant, flushed the core REALLY well, then filled the core/hoses as much as I could before reinstalling them. (retaining as much fluid in the lines as I could.) It helped, but, heater output still wasn't where I thought it should be. It was livable, but, that's it. I am used to my heater being able to burn me out of the truck. My dodge heaters have never been that good.