No Heat

M

Mnkytweet

Member
Joined
Dec 8, 2019
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41
Location
Patuxent River MD
Hi all! Searched through multiple forums for similar issues but couldn't find an answer. I have no heat. Here's what has happened:
2012 JKU 6sp

Almost 4 weeks ago, I changed my oil cooler assembly for a sensor fault. While I had the upper and lower intakes off, I changed spark plugs also. Put everything back together, no leaks, no codes, burped the radiator(a couple of times) until she was regular at operating temp and heat blew strong from all of the vents. Drove it for a couple of days with no issues. Had shoulder surgery, so wasn't able to drive for 2 weeks.

Last weekend(a week after surgery, still couldn't drive), I did a one-armed dash removal and radio change(JVC KW-M150BT, 7 in display...meh). Felt up to driving today, but on our way out, noticed that the heat was blowing ice cold. Got back home and checked all of the usual suspects: radiator was full, both heater hoses were hot to the touch, blend actuator opened and closed according to temp selection. Checked the pins and circuit board on the a/c control, all straight and no signs of arcing.

My only thought is to find a known-good a/c control panel and replace it

Although the weather is turning warmer and this won't matter for another 7-8 months, I'd like to get this fixed before putting the dash back together 100%. Chilton manual is 0 help. Anyone have any ideas?
 
I would try to retrace you steps on the one arm dash removal and what could have happened. Another thing you could try doing is raise the front of the Jeep up high and then check the coolant just maybe there is a air pocket that moved.
 
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BLACKJKU said:
I would try to retrace you steps on the one arm dash removal and what could have happened. Another thing you could try doing is raise the front of the Jeep up high and then check the coolant just maybe there is a air pocket that moved.
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Thanks BlackJKU! I've gone through everything in the dash a couple of times this afternoon and everything was as right as it can be, all things JK considered. I'll try parking on the up-slope in the driveway. I mentioned to my "finance manager" that it did sit for almost 2 weeks in the down-slope direction.

Fingers crossed.
 
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I would try to retrace you steps on the one arm dash removal and what could have happened. Another thing you could try doing is raise the front of the Jeep up high and then check the coolant just maybe there is a air pocket that moved.
Mnkytweet said:
Thanks BlackJKU! I've gone through everything in the dash a couple of times this afternoon and everything was as right as it can be, all things JK considered. I'll try parking on the up-slope in the driveway. I mentioned to my "finance manager" that it did sit for almost 2 weeks in the down-slope direction.

Fingers crossed.
Click to expand...


That could put any air pockets in the heater core.
 
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air pockets in the heater core, OR!!!

My old 2014 developed a personality involving the hvac controls. every once in awhile (I think it was after messing with the radio, which I did a few times) I needed to reset the hvac control positioning. I did this by setting the knobs to the base position. I think it was turning all of the to the left. Then pull the fuse and replace, I think J14 but it's been a few years. Start with the knobs in that position, You should hear the blend doors moving when you turn the ignition.

It is worth a try as it takes 30 seconds.
 
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I'll try that while burping the radiator again

20210315_125805.jpg
 
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That should work, I don't have any curbs near me to be able to work on my vehicles like that.
 
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Yeah, it was a cold (35) drive into work this morning.

And I hate computer stuff! I tried the a/c control reset(multiple ways) and its still blowing cold. I'll have time for another burp just before heading home today. We'll see what happens
 
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Mnkytweet said:
Yeah, it was a cold (35) drive into work this morning.

And I hate computer stuff! I tried the a/c control reset(multiple ways) and its still blowing cold. I'll have time for another burp just before heading home today. We'll see what happens
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Your not the only one that hates computer controlled vehicles, I'll take my 2 12v Cummins vehicles any day over my JKU.
 
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without starting the vehicle turn the key on and turn the heater / ac blend door control. Listen to see if it is moving. It is possible that you got something (this is unlikely) in the way of the mechanism when installing the radio. Or that something else is wrong.

That being said, I really think you have a stubborn air pocket. Good luck and may the heat be with you.
 
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Ran it for almost an hour with the front jacked up, rad cap off and a/c set to full hot. Still blowing cold.

Checked all of the fuses in addition to trying the control panel "reset" again that MacGuyver suggested.

Question: Could this be a sign of a blocked heater core? The heater lines in the engine compartment and under the dash are (very) hot to the touch. I can hear the actuators(blend doors?) moving under the dash, which leads me to believe the control panel is okay. The heater core is the only thing I can think of.
 
When MY heater core plugged up on my Ford one of the heater hoses was pretty hot which would have been in. And the return wasn't warm and could hold my hand on it.
 
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yeah, this could totally be a blocked core.

this is a pretty easy fix and I did my 2009 again a few weeks ago, heater was working, but it started working much better after that.. Garden hose and a bucket.

another question would be what version of coolant are you using?

I personally have stopped using anything but the universal. The engineers that invented a new coolant, that if mixed with the old stuff will turn into gel and block your engine up can straight up burn in hell for the rest of eternity. Straight to dante's deepest level.
 
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When I did my core I flushed it out with hose pressure then took a air hose and tried blowing out as much water as possible. The poured in CLR until it was full and let it sit overnight. Next morning flushed it out into a bucket so I could see if anything came out.

After the CLR was all out reconnected the hoses and then topped off the coolant while trying to get the air out. Went for a drive and it got so hot in there like it was a new truck.

Might add when you first flush it out reverse flush so your pushing out anything that might be plugging it up.
 
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Mine wasn't fully blocked, just not as warm as I would like.

I just used water, both directions then hooked it back up and messed around for the typical 30 mins trying to get the air bubble out. I may try the CLR trick this summer when it's warm out and I'm not in a rush to not be outside.
 
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MacGuyver said:
yeah, this could totally be a blocked core.

this is a pretty easy fix and I did my 2009 again a few weeks ago, heater was working, but it started working much better after that.. Garden hose and a bucket.

another question would be what version of coolant are you using?

I personally have stopped using anything but the universal. The engineers that invented a new coolant, that if mixed with the old stuff will turn into gel and block your engine up can straight up burn in hell for the rest of eternity. Straight to dante's deepest level.
Click to expand...
Yea I agree the same with polyurea grease mixed with lithium grease and it forms crystals like sand and will destroy bearings and other things.
 
Yeah. Kind of a head scratcher turned face palm. I pray I'm the last person that deals with this problem.

Again, Thanks! Especially for the lack of "I told you so"s across the entire forum. There's a wealth of knowledge(mixed with humor, humility, and understanding) on these boards
 
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