Yes, it could also be a controls issue. I know some other members here have had problems with the cables behind the dash that operate the a/c & heating ducts.
When it's super cold out (been in the negative F temps the last several nights) I can't get the knob to stay on the far right defrost setting until the cab warms up a bit.

 

Have the same issues here when the temperatures drops into the -C. However, once the JK heater is blowing hot air...I kinda feel like this guy!

 

^^ seriously! The heat comes out somewhere between 437 degrees and 438 desgrees. I love how hot that thing gets!


Anyway to the OP

Have you taken your dash our recently? Or at all I guess. I messed up my cable a little by taking my dash out and had to take it back out and adjust the cables.

G'luck

 

id say check the blend door and cable... its very easy to go out of adjustment on these vehicles....

like everyone else mine blows burning hot air. (and in summer ICEY cold air after my A/C mod)..

while sitting eating lunch with the jeep running one day i measured 195 degree air from the vents on high fan....

-Christopher

 

So I took it to the dealer this morning around 7 am, I called the service dept at 11 am and spoke with the rep. He said they have been looking at my jeep for about 2 hours and they can't seem to find the problem. He said it's not any of the typical stuff...whatever that means.
I did check to make sure my ac was not running as I had a oproblem with that this past summer that they fixed.
It was a cold 45 minute drive to the dealer this moring as it was only 25 degrees.
Should I call the dealer and let them know some of your ideas or do you think they will just blow me off?

 

i would tell them if they cant find the problem then they better start replacing the whole heater system under warranty. thats just me though. i dont deal well with dealerships, i get very nasty to get what i want.

 

haha...I'm just happy that I didn't bother to replace the thermostat yesterday.

 

so after the dealership took off my entire dash board...not joking, they determined that my heater core is the problem. So hopefully they will have my jeep back to me in a few days. I'm not familiar with the location of the heater core...but I would think that it would be easier to access than taking the whole dash off.

 

nope.. heater core is inside the heater box.. in the dash!. fyi engine coolant flows from the block directly into heater core before going through rest of system. before tstat!. so if you got no heat look at fire wall just to driver side of battery. you will see two rubber lines. mine have the metal silver accordian insulator on them. those are your heater lines. they should be very hot. you can flush the heater core by taking them both off and running water throught it.if there not hot and engine is warm you got a clogged heater core. older gc's were notorious for blend doors breaking. did alot of them. hope the jk does not have this prob too....

 

thanks for the reply, apparently there is a problem with the heater cores as they are on back order. The shop hopes to have it in by Monday.