My heat isn't exactly hot, more like warm-ish

Jon Wildes

Jon Wildes

TJ Padawan
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Im not sure i there is already a thread for heater issues but i have one. i noticed it wasn't all that hot when it was fall but wasn't too worried. however, now its winter and id like some heat. it blows warm but never really heats up. any ideas would be a help, thanks guys.
 
Sounds like you may need to flush it. That's really the only thing I can think of, as a cooling system that isn't producing enough heat generally means your cooling system isn't operating correctly. Any chance there's a low temp thermostat in it?
 
Chris said:
Sounds like you may need to flush it. That's really the only thing I can think of, as a cooling system that isn't producing enough heat generally means your cooling system isn't operating correctly. Any chance there's a low temp thermostat in it?
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i am not sure about this. i know that the temp gauge is pretty steady when i drive.
 
Jon Wildes said:
i am not sure about this. i know that the temp gauge is pretty steady when i drive.
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What temperature is it indicating? It should be at or very close to 210. If the temperature is lower than that either the thermostat has failed/stuck open or someone installed too low of a temperature model of thermostat. It must have a 195 degree rating, avoid 165 and 180 degree thermostats. Also avoid any thermostat labeled as "fail-safe" as those like to fail in the open position. Stant is a good brand of thermostat to go with, Stant's upgraded SuperStat would be a great choice.
 
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Replace the thermostat, they can and do fail. Flush the heater core and entire cooling system with cascade, until discharge water is clear and clean. You can fill up with cascade and distilled water and do a short drive to circulate the cleaner around. May take a few rounds. Do not leave pure water in overnight, as it will freeze and bust your engine block.

If all of the above doesn't get you heat quick enough, you can block off air flow to your radiator with cardboard in increments, make sure your temp gauge works, and verify with a laser IR temp gun.

We use the cardboard trick on our M939 5 ton military trucks, and my Freightliner dump trucks. It is so easy on them, because the hood tilts open, and you just place a sheet of cardboard in there, creating a homemade winterfront. Makes a big difference.
 
For what its worth I flushed the heater core of my old WJ cherokee using vinegar/water and an air compressor on a low PSI setting to force it through. I didn't have a pump like the posted thread, it worked great. I went from barely luke warm heat back to scalding hot. The rub was I had to do the work in some SUPER cold temps but it was worth it.
 
Jerry Bransford said:
What temperature is it indicating? It should be at or very close to 210. If the temperature is lower than that either the thermostat has failed/stuck open or someone installed too low of a temperature model of thermostat. It must have a 195 degree rating, avoid 165 and 180 degree thermostats. Also avoid any thermostat labeled as "fail-safe" as those like to fail in the open position. Stant is a good brand of thermostat to go with, Stant's upgraded SuperStat would be a great choice.
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well i kept an eye on the gauge and when its working properly its right around 210. however it likes to hang out at 0 sometimes until i shut the jeep off then restart.
 
Jon Wildes said:
well i kept an eye on the gauge and when its working properly its right around 210. however it likes to hang out at 0 sometimes until i shut the jeep off then restart.
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Jon Wildes said:
well i kept an eye on the gauge and when its working properly its right around 210. however it likes to hang out at 0 sometimes until i shut the jeep off then restart.
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Then that sounds like a heater core flush will likely take care of your issue.
 
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like everyone is saying a heater core flush will probably do the trick. if you have the time might as well do a full cooling system flush while your in there in order to avoid near future contaminants, when i did mine it all came out brown on the first flush. if the flush doesnt work out for you another think to check is the blend door actuator, located just underneath the dash on the passenger side by the lower vents. i believe there is 3 bolts that hold it in one pesky one in the back corner. sometimes this part fails to make a full rotation thus mixing cold air with hot and not allowing the heat to fully engage. good luck
 
dom.robles said:
like everyone is saying a heater core flush will probably do the trick. if you have the time might as well do a full cooling system flush while your in there in order to avoid near future contaminants, when i did mine it all came out brown on the first flush. if the flush doesnt work out for you another think to check is the blend door actuator, located just underneath the dash on the passenger side by the lower vents. i believe there is 3 bolts that hold it in one pesky one in the back corner. sometimes this part fails to make a full rotation thus mixing cold air with hot and not allowing the heat to fully engage. good luck
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Thanks, Dom I just replaced my heater core and the heat was working before but now it's just warm. Since it is a new heater core I do not know if that's the issue.
 
Have you confirmed the blender door opens and closes? Mine doesn't with the slider, but that's an issue with the cable on my 97. I think yours is a servo.

Does is ever blow cold or is it always the same temp?
 
LittleTankTJ said:
Have you confirmed the blender door opens and closes? Mine doesn't with the slider, but that's an issue with the cable on my 97. I think yours is a servo.

Does is ever blow cold or is it always the same temp?
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Thanks for the reply. The door works It gets cold and lukewarm, and I can hear it when it moves if I am still. My thought is there is air in the line that needs to be worked out. Maybe need to flush the coolant system.
 
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