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Discussion Starter #1
I have a 2014 JKU with ~30k miles on it and the basic heat controls (not automatic climate control).

Work performed under warranty:
15k - Water Pump Replaced (was screeching)
25k - Heat stopped working completely, dealer replaced coolant hose & thermostat
27k - heat cold when centered between blue/red (12-o clock), lukewarm all the way up to 1 click below max. At max it is hot. Dealership added coolant, seemed to solve it for a bit. Next day or two, problem back.
30k - heat is usable still, but not a lot of middle range. Tempted to go play with it in a brand new wrangler and use to demonstrate problem with mine.

Tech at one point told me that a friend's had the same issue and they were unable to figure out why.

I swear I get whiffs of coolant when I walk by the engine bay, but don't see anything leaking. I'll take a look at the coolant level tonight when I get home. I'm 6k away from basic warranty ending, but have an extended one (thanks to the forum and Clay!) up to 100k miles. I really want to try to get this resolved before I have a $100 deductible.

Anything I should look for or check on? One more note - when the Jeep is very cold (parked outside in 5-10* weather) the vents on the passenger side make a clicking noise - is the blower over there? It sounds like something is making contact.

This issue has been a PITA.
 

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there was a recall about 3 or 4 years ago on the wrangler on the heater cores they had grit in them from the casting process and the heater core would crack and or clog up could possibly be your problem
 

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Discussion Starter #3
there was a recall about 3 or 4 years ago on the wrangler on the heater cores they had grit in them from the casting process and the heater core would crack and or clog up could possibly be your problem
I had suggested that, and the service manager said he thought that might be the problem too, but then they said the thermostat and piece of hose fixed the problem. I have a hard time getting past the fact that it blows out hot as hell (aka normal) when on the max setting, but then drops off significantly when I go down one click.

I used to ride around with it centered at 12-o-clock, but now it blows cool air when I do that. I have to leave it 3-4 clicks into the red.
 

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There may be an issue with the temp controls. The knob that you turn to adjust the temp... My dealer said they had seem a number of them bad.
 

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There may be an issue with the temp controls. The knob that you turn to adjust the temp... My dealer said they had seem a number of them bad.
^^^This, my neighbor had his replaced, because of this issue!!!!
 

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Just got my heater core replaced in my 13' jk10a. Been fighting the driver side cooler than the passenger side for the last couple of months. First time I took it in, I had the sludge in the revisor many have talked about. Dealer suggested trying the flush first, which they did three times in that one visit. Noticed a slight improvement but not where it used to be. Gave it back to them last week and this time they went for the core replacement. The bottom half of the core was sludged/plugged up. Service tech told me its a third party who tests the cores for Chrysler and their process is to use a stop leak type of mixture when pressuring and testing the system for potential leaks - which he said was fine. The issue, how they purge or clean it out afterwards is the problem. Was told this issue isn't just with the wranglers, they've been dealing with other Chrysler vehicles too. Fortunately, got mine taken care of under extended warranty. Had it been out of warranty, sounds like it would have been costly. The biggest disappoint is this is a well known issue/problem but there hasn't been a recall or any type of coverage for it - if you're out of warranty and are having the problem, sounds like it'll cost you. The service guy also told me he and a couple other techs made a potent drain cleaner type of mixture and let it set over night in a core they replaced for someone else - based on the way the cores are designed now, it couldn't penetrate through even with an air purge behind it. He seemed more disgusted with the design of the core today than what they used to be. Not sure what they used to be designed like, but today it's essentially two rails on the side and some horizontals running across them - like a mini section of train track. The further at the end of this, is where the problem resides which is why it typically affects the drivers side. How true any of this is, no clue. But he's the same guy who replaced mine - took 9 hours. I guess I also consider myself fortunate in the fact I have no rattles or squeaks in the dash after it was all pulled to get at the core & replace it.
 

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I'll bet your heater core is pretty clogged. At max setting brute force gets enough flow to get hot air happening, but at lower settings there's not enough flow. If not that, then perhaps temp control panel as mentioned.
 

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I highly doubt this problem is at all related to the heater core or any other liquid cooling system components. If the heater core was not getting adequate hot water due to a clog or leak, the temperature would not go to blazing hot at the full hot setting. It would be luke warm through the entire range. If it was an airflow blockage through the core, you would notice the reduced volume of air blowing and it would be very very obvious.

This screams blend door malfunction. It is quite likely the knob. It is rheostat of some kind that drives the electric blend door actuator. The electric blend door actuator is basically a motor or servo that moves an air damper, directing airflow through or around the heater core. If the simple stupid knob is defective, it will never do what it is supposed to do.

I'm not intimately familiar with all these component specifics on the Jeep. But I've been down this road plenty of times with Fords. It's all the same general concept.
 

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It could be the heater controls, blend door, and or a bad heater core. I would have them pressure test the system for leaks, that might reveal the source of the smell. As far as the temperature problem that's either the heater controls or a partially or fully plugged up heater core.
 

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The symptoms described by the OP preclude this from being a clogged heater core or any other coolant flow issue. With the knob set for full hot, the heat gets hot as it should. One click to the left and it drops back down to luke warm. It is not possible for a heater core, clog, or flow problem to cause this. Actually quite the opposite as a matter of fact.

This is a knob or blend door actuator problem, guaranteed. With the knob at full hot, it is likely the 0 ohm direct contact, whereas the rest of the range is part of the rheostat's resistance range. Think of it just like a light dimmer that is all screwed up across the dimming range, but works fine when clicked to 100%.

This might require some hand holding at the dealer to get them to comprehend this. But symptoms, cause, and effect logic points right to it.
 

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The symptoms described by the OP preclude this from being a clogged heater core or any other coolant flow issue. With the knob set for full hot, the heat gets hot as it should. One click to the left and it drops back down to luke warm. It is not possible for a heater core, clog, or flow problem to cause this. Actually quite the opposite as a matter of fact.

This is a knob or blend door actuator problem, guaranteed. With the knob at full hot, it is likely the 0 ohm direct contact, whereas the rest of the range is part of the rheostat's resistance range. Think of it just like a light dimmer that is all screwed up across the dimming range, but works fine when clicked to 100%.

This might require some hand holding at the dealer to get them to comprehend this. But symptoms, cause, and effect logic points right to it.

Good points. I mentioned pressure testing and the heater core because of the "possible" coolant smell he mentioned.
 

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Discussion Starter #12
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So after multiple trips with the dealer saying I'm crazy/it's normal, my heat completely stopped blowing warm (again) over the weekend. Dropped off at dealer, picked up same day.

The blend door actuator had failed - I suspect it was failing, and that may explain some of the clicking sound I had before too. My heat is back to normal, hot as ever, and I'm pretty sure I have the whole range again.
 

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I had the same problem.....I had mud packed in the bottom half of the radiator. Even the dealer didn't see it. i cleaned out the radiator everything dropped to normal. Dealer had already replaced fan and was getting ready to break engine a part.
 
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