Engine heating but heater not heating

JoeTheCarGuy

JoeTheCarGuy

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Joined
Sep 15, 2017
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Location
Alabama, United States
Hello all, my employer just bought a crisp clean 06 LJ, 4.0 6 spd manual. Like all used vehicles it has a few little trouble areas. The first and most inconvenient one is the HVAC heat not functioning. Seller did say that the heater core was just replaced. Fan motor resister works as it should. Engine heats up to the normal 210 degrees, both heater hoses are hot to the touch. Cold air through all of the vent selections at all times. Could it be electrical? No vacuum leaks or sounds. Any help would be greatly appreciated.
 
Blend door actuator for the hot/cold probably not working or maybe wasn't hooked back up when the heater core was changed.

I'm going to guess the heater core was changed because of this issue when in reality the heater core wasn't the problem. But that's just a guess.
 
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machoheadgames said:
Blend door actuator for the hot/cold probably not working or maybe wasn't hooked back up when the heater core was changed.

I'm going to guess the heater core was changed because of this issue when in reality the heater core wasn't the problem. But that's just a guess.
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That blend door is controlled by vacuum or electric motor?
 
machoheadgames said:
Don't quote me on it, but I think they were vacuum for 97-02 and went to electric 2003-2006. But I would need to check the factory service manual for 2006.
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The blend door actuator is electric on my '01.

F04055_Front__ra_p.jpg
 
CharlesHS said:
The blend door actuator is electric on my '01.

View attachment 314503
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I guess it wasn't as simple as early vs late being all or none on vacuum then.

The recirculation door was vacuum on a 2006. blend door was electric. Looks like there are two vacuum actuators for the mode selection as well.

So in this case, the one he needs would be the electric blend door actuator.
 
The blend motor seems to be functioning as evidence in this short video clip. I didn't pull the shaft to see if the nylon shaft was striped. I guess I need to go back and check that.
 
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JoeTheCarGuy said:
Yeah, me neither. I thought it may have to be viewed and approved by someone before it would actually post.
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I see the video now. Looks like the motor is working, though I can't tell if it's actually moving anything on the heater box?

I suppose a lot of times those bolt straight to the shaft on the flap so you won't see any operation from that view. Assuming it is operating the flap then, the next thing to check would be to make sure you have coolant in both heater hoses going to the heater core. Are the hoses getting hot?
 
Mall'er said:
Can't tell from the video, but is the pin in the blend motor? Usually three screws to remove, but it looks like you already have fewer.

You can see the pin in this link.

https://www.amazon.com/dp/B00FOOU6HE/?tag=wranglerorg-20
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Yes, I pulled the actuator, removed the 3 screws. The pin or shaft does indeed fit into the actuator and it does move the door. I twisted the shaft and moved blend door by hand. Both heater hoses do get hot, there is about a 15-16 degree drop from the intake line to the exit line. The air temp that does exit the defroster vent is 86 degrees max. We have a second tj to use as comparison, it has the same 15-16 degree temp drop but the air temp at the defrost vent is 156 degrees. My logic says that the air flow through the heater core is restricted some how. I'm not sure what the vacuum actuators operate, vent selection I know but I'm not sure about the temp selection.
 
JoeTheCarGuy said:
Yes, I pulled the actuator, removed the 3 screws. The pin or shaft does indeed fit into the actuator and it does move the door. I twisted the shaft and moved blend door by hand. Both heater hoses do get hot, there is about a 15-16 degree drop from the intake line to the exit line. The air temp that does exit the defroster vent is 86 degrees max. We have a second tj to use as comparison, it has the same 15-16 degree temp drop but the air temp at the defrost vent is 156 degrees. My logic says that the air flow through the heater core is restricted some how. I'm not sure what the vacuum actuators operate, vent selection I know but I'm not sure about the temp selection.
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The vacuum actuators are for choosing fresh air/recirc air, and for blowing towards defrost/chest/floor. So they aren't the problem.

There are no heater valves that stop coolant from going into the core when the heater is off, so maybe you do have a block, but that seems highly unlikely since you're getting hot water on both hoses, indicating that the coolant circuit through the heater core is working. Really bizarre problem.
 
machoheadgames said:
The vacuum actuators are for choosing fresh air/recirc air, and for blowing towards defrost/chest/floor. So they aren't the problem.

There are no heater valves that stop coolant from going into the core when the heater is off, so maybe you do have a block, but that seems highly unlikely since you're getting hot water on both hoses, indicating that the coolant circuit through the heater core is working. Really bizarre problem.
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I would see if the inlet to the core was the same temperature as the one on the test tj
 
machoheadgames said:
The vacuum actuators are for choosing fresh air/recirc air, and for blowing towards defrost/chest/floor. So they aren't the problem.

There are no heater valves that stop coolant from going into the core when the heater is off, so maybe you do have a block, but that seems highly unlikely since you're getting hot water on both hoses, indicating that the coolant circuit through the heater core is working. Really bizarre problem.
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It has me puzzled for sure! Thank you for your time and information!
 
Another question, different part , same problem. Who manufactures the thermostat for Mopar? We just picked up a new one from our local dealership, it is stamped “MotoRad”. I questioned the salesman and he said that’s the way they came. I’m skeptical
 
JoeTheCarGuy said:
Another question, different part , same problem. Who manufactures the thermostat for Mopar? We just picked up a new one from our local dealership, it is stamped “MotoRad”. I questioned the salesman and he said that’s the way they came. I’m skeptical
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When I replaced mine a couple years ago the local mom and pop parts store said MotoRad bought Stant.
 
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