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Old 09-29-2014, 11:51 PM
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2012 jku NO heat at all!

So I work 3pm-11pm and when I got off work tonight it was 52 degrees outside.. I turned my heat all the way to hot and the blower 1/2 of the way up. After 30min of driving.. I still have no heat at all. I tried finding something about it but I haven't found anyone with no heat at all. Everyone just has little heat. I have no antifreeze smell. The jeep has 43,000 miles on it. Thanks for any help!

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Old 09-30-2014, 01:44 PM
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Anyone have any ideas?

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Old 09-30-2014, 03:29 PM   #3
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Pull the glovebox out. Turn the knob from cold to hot and see if there is any movement on the air controller. If not, you have a cable loose. If there is movement, then you may have a blocked heater core. You would be in the same category as the little heat folks. A lack of heat is just that.

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Old 09-30-2014, 04:32 PM   #4
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Check your antifreeze level
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Old 09-30-2014, 04:53 PM   #5
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Quote:
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Check your antifreeze level
what he said.. ^
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Old 09-30-2014, 09:39 PM   #6
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I had the same issue. I checked all the heater core hoses to make sure they were getting hot. Then took the glove box out and pulled the connections off and back on and it started working. The kicker is making sure your get movement out the mixer door. Most of the guys with heater core issues had just a little heat or heat on one side.
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Old 09-30-2014, 11:37 PM   #7
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I have a 2012 and it had the blocked up heater core issue that many here have had.

While it's a great idea to try the simple fixes first, if they don't fix the issue you'll more than likely need to take it in an have them replace the heater core under warranty. And don't let them diagnose it without showing your service manager that that the temperature gauge is up to normal and you're not getting heat. When I took mine in, they let it idle for like an hour with the heat off so the core would get nice and heat soaked and then turned the heat on. That gave them a false reading on the temperature coming out of the heater. Make the service adviser get in the drivers seat and check it out as soon as you bring it in so that he can see the problem first hand. Once I did that, they finally caved and replaced the heater core, along with the radiator and a full flush of the engine.
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Old 10-04-2014, 08:03 PM
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So I flushed the core today and had plenty of water flow thru it so I'm assuming that it is the blend door for sure. Anyway you can access it without removing the whole dash? I know that in the tj's you can cut a hole and access it thru the hole then glue it back up. Thanks for any help!
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Old 10-04-2014, 08:41 PM
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And I checked the antifreeze level and all was good. Thanks for the input
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Old 10-04-2014, 09:54 PM   #10
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So I flushed the core today and had plenty of water flow thru it so I'm assuming that it is the blend door for sure. Anyway you can access it without removing the whole dash? I know that in the tj's you can cut a hole and access it thru the hole then glue it back up. Thanks for any help!
You can flush a lot of water through the heater core but still have a buildup of sediment in it. They flushed mine twice before finally replacing it. And they had to remove the entire dash to replace it.
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Old 10-05-2014, 09:17 PM   #11
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Did you happen to put a filter over the other side of the core as you were flushing it? I flushed mine with a white rag over the other end and I collected a TON of particles in the rag. After flushing it back and forth a few times it came out clean and there was a noticeable difference in my heat. However, I've had to do this a few times and continue to get the "sediment". Sadly my jk has a reconstructed title and no longer has a warranty so no dealer will help it without costing me an arm and a leg.
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Old 10-05-2014, 09:18 PM   #12
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Sorry, meant to say that I had plenty of water flow as well.
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Old 10-05-2014, 09:29 PM   #13
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You need to make sure both heater hoses are hot. If one is and the other is not the heater core is plugged up. When I flush heater cores at my shop we also run compressed air through them. Another reason you may not have heat is there is air in the cooling system. If all that checks out you may have a blend air door issue.
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Old 10-06-2014, 07:23 PM
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If I reach under the dash and grab the heater core lines they are both very hot. I'm going to take the dash out this coming weekend to see what's up. Also I noticed my rear defrost light i s flashing after start up.. I'm guessing blend door now.
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Old 10-06-2014, 08:55 PM   #15
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Just because the lines are hot doesn't mean that the heater core isn't partially blocked by sediment. In fact, the return line should be noticeably cooler than the supply line when you're running the heat full bore. If they're both very hot when the heat is on high, there's no heat being extracted when it's passing through the core and it's either the door or a partially obstructed core that's at fault. Depending on the exact design of the heater core, it's possible to get a lot of sediment built up but still have plenty of water flowing through the core.
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Old 10-06-2014, 09:11 PM   #16
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Looking at the picture from rock auto, you can see how the sediment could build up in the heater core but water can still get through:

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Old 10-09-2014, 01:26 AM
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Thanks so much guys! Does anyone know where to find instructions on the dash removal? I've done countless searches but can't really come up with anything.. I guess I'm going to go ahead an buy a heater core as well being that they seam to not be very reliable from some of my searches. Thanks so much!
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Old 10-09-2014, 06:10 PM   #18
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Best bet would probably be to buy a repair manual. I use Mitchell OnDemand, but my shop pays for that.
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Old 10-10-2014, 01:07 AM
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I'm looking at like 150 for the manual.. I wish I could just find a write up for it lol

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