Cutman

I've been doing my research on why my 2014 JK heater was only working when I was driving. It starts blowing cold at idle. It seemed a large number of you solved this issue by doing a heater core flush. Others argue that is NOT the case. I opted to try it. I invested about $30 in hoses and psets etc and gave it a whirl. Now I have no hot air at all. I replaced my thermostat a year or two ago. That was pretty cheap and painless. I may just do that again for S n G. Anybody else have 2 cents to throw in? I'm fairly handy and not afraid to take sh%t apart to save some money. Especially seeing as how quite a few people went to the stealership with this and are still having the issue.

Dirt Hammer

Given the fact you flushed the heater core and now lost all heat would lead me to believe your cooling system is not properly filled with coolant. Do you have the digital engine temp read out option? What's the engine temp? What was the results of the heater core flush? debris? how well did it flow?

resharp001

I tend to agree. The fact that it was warm while driving but cool at idle makes me think there is air in the system. While accelerating, there's enough movement to push coolant through but not while idling. Are you positive you got that thing bled well? Sometimes bleeding the air out can be a hassle that takes a couple attempts. Hopefully it is something simple and not an actual heater core replacement.

Freedom21

Remove the radiator cap and start the engine. Give the upper radiator hose a few squeezes. You will be able to feel if it's full of air or antifreeze. A few squeezes should move the air pocket and you will be able to top off the antifreeze. I've done this on a couple vehicles that had the hot/cold issue. Worked both times. Hopefully this easy fix will work for you as well.

resharp001

The only thing I'd disagree about here is if OP has no heat at all, the air would be trapped in the heater core, at which point it's a little different than just general air in the cooling system. There are vids on YouTube though that help show how to force air out of the core itself via different rev cycle variations. I've had to do similar on a couple different vehicles and worked well. It is just a little tricker than a normal bleed. Also, out 3.6L have a bleed screw at the thermostat housing which can help too.

Dirt Hammer

Just remembered one other issue I had..... The radiator cap has a vent built into it, designed to vent as the cooling system cools down. Mine had sludge built up in the vent and not allowing it to vent. Result was a sucked flat top radiator hose.

I found sludge under that round disc

Cutman

So day 2: After running the heat every time I get in the Jeep, it has slowly started working again. Probably had to work the air out of the lines. It even seems to be running hotter than before. And it's staying hot at idle. I'll see if the radiator cap is clogged and also if it needs to be topped off now. I'd imagine it does. I'm sitting at the bus stop waiting for my kid as I respond, and I'm sweating my ⚾⚾ off. At idle. Thanks for the input fellas. Happy Jeeping.

Dirt Hammer

glad you got it working....

Rednroll

Yep, your symptoms sounded like low coolant (aka air in the system). Once you get it filled and burped properly where the JK can self burb as you drive, the heat will start to flow again. However, now that you got the heat fixed due to low coolant, what you will want to figure out is the reason it was low in the 1st place. You may have a leak somewhere. Time to do a pressure test.

Radiator, thermostat housing, and cracked oil cooler housing are some of the more common sources of coolant leaks on a 2014 JK.

mpauls

Question from a new owner.
How does one setup the coolant system to " self -burp " itself. ? Or am I missing something and it's just the way a JK is designed?
Thanks for any help !