Ok, I live in wet western Oregon, never had an issue with heat or defrost down into the 20's. Went to eastern Washington, temp was single digits, drove for hours at highway speeds, my wife and I were warm from the waist up and in the front. The back seat area was freezing and that cold air just chilled us. There was also condensation everywhere in the back. I tried every combination of heat/defrost available. Then it started to rain which instantly froze on the windshield. Fan on high, temp on high and full defrost chosen would only keep the lower half of the windshield clear and my wipers froze up and stuck every wipe. I have the auto temp control. Has anyone else had any issues like this?

 

Check your coolant level. Just had this in my 14' single digit temps and the "rotisserie" as my wife calls it wasn't quite performing . Was a good bit below the MIN line in the resivoir. Added some coolant and we're back in business.

Start there as it's the cheapest fix but make sure you put the right stuff in so check your owners manu. If you add and lose OR still don't get heat then have system flushed and monitor for leaks.

 

Most of the time if the coolant is low enough to cause heat issues you will hear a gurgling sound when you first start it up.

My gf's JK use to eat antifreeze. When it gurgled I knew it was time to top it off. Typically thats too late as you should check your fluids more often....

 

Just an idea, if you have a hard top, do you have the insulation liners installed? Hot Headliners make some good ones. They're designed to keep the heat out, but also work well in the winter to keep the heat in. The hardtop loses alot of heat, and if you touch it, it is very cold!

 

I had a several heat problems in last few months. Cleaned and flushed the entire system.... that fixed colder air on drivers side when compared to passenger. This worked great for a month then the entire system got much cooler. Fluid was good, no air in the system... this lead to a problematic thermostat. So I ordered a new one replaced it and topped off the coolant again. Now the heat is screaming hot. Now this is what I don't get l boiled the thermostat it never opened at all. The jeep always ran 190 degrees which would lead me to believe it should be stuck open. My jeep is a 2012 and everywhere I looked it calls for a 203 degree thermostat. So if anyone can explain that!! But I would look at replacing your thermostat they are not very expensive if you do it yourself. Also for the sake doing it I also replaced the radiator cap.

 

This is a well known problem with JKs. The issue is a failed actuator that needs to be replaced. The actuator blends hot air with heated air from the heater core. When it gets stuck you won't be able to adjust the temperature. I had this problem with my '14 JK and had the dealer replace the actuator under warranty which solved the problem. I don't know what the cost would be if the warranty wasn't still in force.

 

This last question made me just chuckle. Currently, heater related problems are probably the most common problem discussed in this section of the forum.

You're getting a lot of suggestions on how to fix, based on everyone else's personal experience but you'll find there are many different fixes out there and the symptoms are all very similar to what you described.

You might want to start by reading the same question asked thread that I started where I called out the majority of potential diagnosis after reading MANY different heater related discussions.

https://www.jk-forum.com/forums/stoc...roblem-339178/

Radiator cap, clogged/bad heater core, thermostat, blend doors, vent actuators, low coolant, casting sand, air in the cooling system, air cabin filter clogged, leaking radiator, mixed coolant types.....they're all in play. Good luck!!!

Let us know what fixes your heater problem, I'll let you know what fixes mine "if" I ever get it fixed.

 

Thanks everyone for the responses. I just want to point out that this issue is not on my old '07 (as my username suggests, don't know how to change that) but my '15 Rubicon with only 17k miles. I'm in the process of moving to the colder area but fortunately (I hope) there is a Jeep dealer in the little town I'm looking at living in. They should have seen every heating system problem there is by now. Insulation liners are going to go in before next winter for sure, as well as seat heaters! My biggest concern was that the system couldn't keep the windshield clear of ice, even at full fan and highest temp on full defrost. It was single digits and raining but I haven't seen this happen before on any other rig I've owned. Thanks again.

 

A lot of us live in colder states but we didn't experience the same storm as yourself. So it's hard to say, if we've seen the same problem because we're not exactly sure of the exact weather conditions. Heater related problems, there are plenty and there's not one magic bullet that points to one particular item to fix. You should start by checking your coolant level as previously suggested, topping off and burbing the system and then go from there.