We have been having problems with our heat not working on our 2003 Dodge 2500. It had no heat for a while so we thought it was the blender doors since we had to replace 2 other blender doors in the truck. We did not want to crack the plastic so we brought it to a dealership to have them replace the doors for us. They told us that it was not the doors but it was the heater core. So we had them replace the heater core and we had them put in all the doors that have not been replaced yet since the dash was already apart. We got it back and there was still no heat. They flushed the entire motor and radiator and put all new coolant in. They also found a pin hole leak on the radiator so we replaced that since it was still under warranty because it was only a year old. We still had no heat after that so we brought it back in and they could not find out what was wrong. We now have luke warm air coming from the head and foot vents when the thermostat is in between hot and cold but is cold on the cold side and is also cold on the hot side. So we though maybe it was the thermostat switch that was bad so we took one out of our other truck that is also a 2003 dodge ram 2500 with a 5.7 Hemi. It was still only luke warm air in the middle of the thermostat, and cold on the hot side of the thermostat. Also when we put the defrost on, it only blows cold air. I just flushed the heater core again and it was all good. The heater hose lines were 170 and 130 when I took there temps. Any Ideas on what could be making this truck not blow hot air?

 

how do I post a question???

 

What is this tube coming through the firewall circled in yellow? It’s leaking coolant.

Also found coolant in areas circled in purple. Coolant smell inside cab.

 

The tube coming thru the firewall is the condensate drain for the a/c. With the a/c running, it's normal for water to drip out there. If it's actually coolant... then likely the heater core is bad.

Coolant leaking in those locations on the engine though... that might be a bad head gasket. Unless it is running down there from somewhere else?

 

I also have a 2003 dodge 1500 and the heat disappeared. Replaced the thermostat, no heat. Measured the temps into and out of the heater core...roughly 165 degrees on both, so the heater core isn't clogged. Watched numerous videos on checking the blend door and it is functional...but it only moves when the blower is turned on. It doesn't move when the temp control is moved. My temp control does move another actuator arm but I cannot see if the arm is connected inside and/or moving. I shut the blend door (to outside air) and disconnected the wiring harness thinking that would allow only hot air to be pushed into the cockpit...no heat. I have a borescope but don't know where to check next. BTW, my a/c also was anemic this summer and I just got used to it. I have windows for the summer, I want heat for the upcoming winter months. Could both issues be related? I BTW am getting very good at removing the glovebox and associated dash panels.

 

The blend doors are usually the major cause ,and there are at least 5 different blend doors all together , there are more places than glove box area ,