Heat Not Working

Joined
Apr 18, 2021
Messages
7
Points
3
Make
Dodge
Model
Ram 2500
Year
2003
Miles
152000
Engine
5.7 Hemi
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 have a heated place to remove the dash and did not want to crack the plastic so we brought it to a dealership to have them replace the doors for us. They told use 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. Any Ideas on what could be making this truck not blow hot air?
 
Joined
Apr 18, 2021
Messages
7
Points
3
A good diagnostic question to be answered is this...when the engine is "all warmed up" are the heater hoses hot to the touch?
I warmed up the engine to normal operating temp and took the temps of the heater hoses. One was 170 the other one was 100. I will flush the heater core and see if that helps.
 
Joined
Apr 18, 2021
Messages
7
Points
3
I warmed up the engine to normal operating temp and took the temps of the heater hoses. One was 170 the other one was 100. I will flush the heater core and see if that helps.
I flushed the heater core and it was all good, which was expected because it was just replaced and all the antifreeze was just replaced. I also retook the temps of the lines with a temp gun and one was 170 and the other was 130. Still no heat
 
Last edited:

Mobile Dan

wrench
Joined
Mar 1, 2002
Messages
3,787
Points
48
Location
Kentucky
170 seems somewhat low for the "hotter hose", but I would think that warm air should be happening. So you likely have a flow problem. Coolant not pushed through the core by the water pump, or air not being pushed through the core by the blower fan. Perhaps you still have a blend-air door problem?
 
Joined
Apr 18, 2021
Messages
7
Points
3
I
170 seems somewhat low for the "hotter hose", but I would think that warm air should be happening. So you likely have a flow problem. Coolant not pushed through the core by the water pump, or air not being pushed through the core by the blower fan. Perhaps you still have a blend-air door problem?
Is there anyway to find out if you do with out taring the dash out?
 
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