Battling this myself right now... So many possibilities.
1 - Thermostat could be stuck in the open position and might need replaced
2 - Have you done anything to the coolant since the last time? If you have could be air in the system
3 - Blend door - Do some searches and test before going through the trouble of replacing...it is a pain.
3 - Heater Core is clogged, requires you to blow out the heater core. My plan this weekend end is to disconnect the tubes and blow air at 30 PSI through it both ways and hopefully that will unclog it and get the coolant flowing right
4 - Worst Case...Heater core needs replaced... you can do the research there are easier ways to do it but both are a job...dealership you are looking at a pretty big job from what I have read.

 

I would be careful pushing 30 PSI through the heater core, the cooling system is only designed to have 16PSI running through it (probably up to 20PSI for safety)


as for the issue in question is heat only on one side of the Jeep or is it cold air on both sides?

if you have heat on one side only it is hands down clogged heater core as that is a common symptom and my Jeep was one that sadly had this issue befall it, thankfully I was able to resolve it pretty easily.

 

We're sorry to hear about your A/C concern. Are you considering having your dealer take a look? If so, we are available via PM to offer additional assistance.
Alex
JeepCares

 

We're sorry to hear about your A/C concern. Are you considering having your dealer take a look? If so, we are available via PM to offer additional assistance.
Alex
JeepCares

Yes, I am taking it to SJ Denham with our Max Care coverage, it should only cost the $100 deductible.

My Jeep dealer is



SJ Denham Jeep in Redding California.



a/c is working fine. Heater is not working.
Could not see any sediment in coolant tank.

 

Check to see if you have sand/sediment in your coolant overflow tank. Could be casting sand (extensive info on forum about this) or possibly had oat and hoat mixed, sludging up the cooling system.

My '13 JKU had this same issue about 18 months after I purchased it. Turned out to be the casting sand issue. Required coolant system flush and replacing radiator, heater core and water pump. Fortunately under warranty.

 

I have a 2017 Wrangler. Same thing. They had to replace my heater core. Now the heat is great.

 

I have a weird issue. Heater feels like it starts out fine set at like 76, then feels like it starts blowing cooler. If I turn it all the way to hot its comes out really hot like you would expect. I have been playing with the fresh air and recycled air and seeing if it makes a difference. I'm still investigating. Unfortunately I did find orange sludge crap in the coolant overflow.ullinghair: I have a 2014 JKU with 35,800 miles on it. I bought it as a Jeep certified vehicle. Not sure dealer will cover it.

 

You likely have mixed coolants which will require a coolant system and heater core flush, then replace with correct coolant.

 

I've kind of got used to this myself. The passenger side is hot, then decreases in temp through the middle only to cold air on the far driver's side. Watched a Youtube vid showing to disconnect a hose close to firewall and pour in coolant, just haven't made the effort yet. Seems common enough that warranty be damned, Jeep needs to cover since its their problem

 

Well, mine magically resolved itself the other day during my hour commute. Prior to that it was getting really bad, just wasn't warming up at all. Odd part it was somewhat warm on the outside vents, center vents were ice....After work, went out to my car, took off and there was heat...haven't checked under the hood to check coolant level, but I'm guessing something unclogged. Not complaining as I have a new thermostat waiting to be installed as that was my next step. Driving with no heat in the NJ/PA is not fun.

 

It still makes no sense to me why the heat is different from the 4 vents. When you see the dispersing apparatus that sits behind the dash, it looks like a single input that branches to the four vents. Our JKs aren't uptodate enough for dual cabin temp control, so it kind of baffles me. Yeah, mine did the same shortly after it first started: couple times heated as normal. Now, I just leave the driver vents closed and aim the passenger vents my way.

I did have casting sand, but has been 4 years I have had my JK and heat issue is this fall. I had replaced the thermostat a year ago due to throwing a temp code. Used Mopar coolant to refill.

 

It still makes no sense to me why the heat is different from the 4 vents. When you see the dispersing apparatus that sits behind the dash, it looks like a single input that branches to the four vents. Our JKs aren't uptodate enough for dual cabin temp control, so it kind of baffles me. Yeah, mine did the same shortly after it first started: couple times heated as normal. Now, I just leave the driver vents closed and aim the passenger vents my way.

I did have casting sand, but has been 4 years I have had my JK and heat issue is this fall. I had replaced the thermostat a year ago due to throwing a temp code. Used Mopar coolant to refill.

There are no mixing vanes in the output chamber. The air flows through the core and stays pretty much lined up as is went it went through in the first place. So the majority of air which came from the top left of the core ends up traveling to the top left most part of the output chamber and then to the top left most output ducting. If the top left of the core is plugged (or air locked) then the vent coming of the top left of the output chamber is colder.

 

I purchased Mopar coolant from our dealership yesterday. Service guy said that our overflow coolant tank was at the minimum line. I filled it to the maximum line which took about a cup of coolant. I let our Jeep cool off and removed the radiator cap and coolant was at the top.

We will see what they find out Wednesday.

Also noticed that after starting our Jeep, the temperature gauge goes to normal very quickly. Not sure that it should show normal in less than 90 seconds after starting with a cold engine.

 

I had an issue when I first bought my Jeep with the upper and lower radiator hoses collapsing and the dealer kept saying there was air in system and bled the system, but it still did it. I kept telling them that the radiator cap was most likely the issue and after the 3rd time when I went to get my Jeep it was still not right, I told the service writer to get the cap from parts and I'll put it on and if it doesn't solve the issue I would pay for it. Well it fixed that issue. I'm just wondering how long the issue was there before I bought the Jeep and if it caused any issues. My temp takes what seems the normal amount of time to rise and I do have great heat when I turn the temp dial all the way to hot. Ive been playing with the recirculate button to see if that keeps the heat even when I set it to 74.

 

I will let everyone know what the dealer finds.

 

Our heater puts out cold air on all outlets.

 

Local dealer found that the door actuator was the problem. They replaced the temp actuator and that fixed the problem.

They also reprogramed the PCM for a recall issue V51.



Since we have lifetime Max Care service, it only cost us the $100 deductible.

They also said that Chrysler is not selling the Max Care policy any more. They were loosing to much money.

































they

 

Local dealer found that the door actuator was the problem. They replaced the temp actuator and that fixed the problem.

They also reprogramed the PCM for a recall issue V51.



Since we have lifetime Max Care service, it only cost us the $100 deductible.

They also said that Chrysler is not selling the Max Care policy any more. They were loosing to much money.

i'm in a 2017 JKU. I had just left the auto detailer in the summer 2019 and as i was driving away i noticed the AC dial was turned to heat but no heat was coming out. on the way home decided to stop at the dealer and they found the same issue. faulty door actuator. they fixed it at no cost to me thankfully, i guess it was covered under warranty, not sure. I was asked by at least 2 people there, you use the heat in the summer? glad it happened when it did. their work load seemed light to me when i arrived.

 

I also had minimal to no driver side heat since this past winter. I was soon fixing to do the dash cutting technique to swap the heater core after troubleshooting everything. Even replaced my radiator which was leaking, coolant hoses, thermostat and no change. Last week was spilling coolant down the bellhousing when I turned my fan on and took to the dealer to diagnosis. They thought heater core at first, but traced the leak up to the oil cooler. I have not once leaked oil, but the bottom plastic piece was obviously cracked as there was pink/white dried coolant caked on the bottom. Replaced the part, and poof, heater is molten lava again.

If you have no driver side heat, I would recommend getting under the Jeep with a light, middle of car and look at the oil pan and transmission case. Above that, you may see dried white drips of coolant, and if so, you will probably need an oil cooler swap. They also replaced the manifold gaskets at the same time. If super lucky, it may be the coolant hose, but labor costs are the same to get to it.

 

Great info! That's the problem with these JK heater discussions. The symptom is always the same of cooler air blowing from the driver's side vent but that all boils down to a simple diagnosis of the heater core not having enough hot coolant inside of it to fully distribute heat across the dash vents. Then you need to get into the real trouble shooting dianosis of determining the reason the HC is either blocked or there is a leak somewhere and therefore has air inside of the HC and therefore the HC is not fully filled with hot coolant. In your scenario, there was a leak in the oil cooler, which led to low coolant and air inside of the HC.

In my particular instance my trouble shooting went like this.
1. Observed cool air was blowing from driver's side vent.
2. Noticed my coolant was low, filled and burped coolant system....heat improved for about 3 days, then cool air again from driver's side vent.
3. Observed coolant was low again, identified leak in radiator, replaced radiator.....heat improved for about 2 weeks, then cool air from driver vent.
3. Observed coolant was low again, identified I had a lower-intake manifold gasket leak, replaced LIM gasket....heat was better for about 2 months.
4. No longer observed coolant was low, but cool air still blowing from driver vent.
5. forward and backward flushed HC, no improvement.
6. removed HC, cut it open and observed it was jam packed with engine casting sand. Replaced HC and finally had heat like I remembered when new. Been good for the past 2 years now.

So the symptom of cool air blowing from driver's side vent was always the same but I ended up performing 4 different fixes before I was able to get heat back to working properly.

 

...I think its because we ALL try really really hard to look the other way, rather than tackle the heater core job!

I've got an automatic 2018 JK Recon, with 17,500 miles. My heater ONLY produced actual heat at max setting. Everything else was cool air. I did the reverse flushing H/C last week, and it worked great for about 1 hours. Back to cool temps throughout the dial, unless it was at max. Then I had molten lava heat!

Today I did a FULL coolant flush (radiator, hoses, engine block, reservoir (lots of sludge on the bottom), new thermostat, heater core (sand-like stuff flowing out), etc....) with some pressurized hoses and used Mopar stock coolant. Burped it for a good 1/2 hours, and I saw TWO cycles of the thermostat.

We'll see. It APPEARED to resolve the heating issue. It's 92* here in Chicago today so it was hard to keep "testing it," but inside the shop it appeared to have the old heating system back: from 66* on the dial to 84* at max setting, it was getting gradually warmer/hotter....once at max, molten lava!

In an unrelated note, the odd thing I notice as a new Jeep owner, is the regular coolant temps as shown on the digital dash reader is between 208* - 228*. Seems hot to me, but the gauge is dead center and apparently everybody seems to run the same temps with JKs

 

I had the full coolant flush and heater core treatment 2 winters ago, plus a new Thermostat ... it fixed the ice cold heat for a season. Near the end of last winter, I started losing heat. I smell coolant every time I park my Jeep in my garage, so I know there is a leak somewhere.

It's pretty sad that so many Jeep owners have the same problem, it's obvious Jeep dropped the ball on this. The cooling system is a weakness that's listed on review sites for the Wrangler.

 

I had the full coolant flush and heater core treatment 2 winters ago, plus a new Thermostat ... it fixed the ice cold heat for a season. Near the end of last winter, I started losing heat. I smell coolant every time I park my Jeep in my garage, so I know there is a leak somewhere.

It's pretty sad that so many Jeep owners have the same problem, it's obvious Jeep dropped the ball on this. The cooling system is a weakness that's listed on review sites for the Wrangler.

Just make sure if you take it to the dealer they don't just assume heater core is bad. That is a much more expensive fix and requires a dash pull. I was going to do the shortcut, dash-cut, method posted on here if mine was truly bad. My problems started exactly as yours is now, and required a oil cooler change. Coolant smell and loss somewhere. Good luck to you

 

Also as many have missed.. sounds crazy but check the coolant level. If it’s low it will cause it to not blow heat.. I had the same problem. Ended up being a tiny drip on the back side of the radiator. Coolant would slowly drip off just enough for the heat to stop working.

 

Not to trample all over your helpful comment, but this thread is 4 years old so either the issue's been fixed (I hope!) or the OP traded his Jeep in out of frustration.