Well winter is rolling in very soon in Michigan and I just tried using my heat and it blows cold air. This worries me because with a soft top in the winter I will have to wear gloves and goggles to drive to class! Any ideas on why the Cold A/C works fine but the heat does not??

 

Check for coolant leak? Is the heater hoses that run through the fire wall (BOTH of them) hot when the engine is at operating temperature?

Could also be the blender door.

 

If one hose going to the heater core is hot but the other is not then maybe your heater core is clogged or blocked.

Or as mentioned above the door that controls airflow temperature then you turn the knob..

 

yup, I should have been more clear on that in my post. I hope that's not the case for the OP...

 

only one tube is hot, so blockage??

 

If the vehicle is warmed up, both hoses should be warm or hot. The return line might not be as warm as the other but ya both should be pretty warm. At least they are on my Jeep.

There have been people successfully flush the heater core. I would search around. When I googled "flushing jeep wrangler heater core" I got multiple hits including videos.

You might want to have a good mechanic look at it before doing anything though, to make sure it is not something else.

I have read that the core on a JK is tough to replace, involving removal of a lot of the dash.

 

yup... have to pull the battery, the battery tray, the steering column, the console, then the dash comes out... then you can pull the core off the dash and replace it.

 

Is there any sediment in your coolant reservoir? I had some at the bottom of mine and I had my coolant flushed. It didn't help. This sediment could be clogging your core.
My next step is to try and reverse flush the system, which seems easy enough. I haven't completely lost my heat, but it doesn't blow nearly as hot as it did when it was new.

 

before ripping apart the dash make sure its not somethng simple like the cable (if you have 10 or older) on the hot / cold dial has possibly become disconnected or severely ,mis-adjusted. on the newer (11+) jeeps it is electronic blend door and the HVAC dash control on those is known to go bad!..

the older ones its just a cable linkage to a door in the ductwork and over the summer things can work loose because you typically put it on cold and forget about it all summer.. .looking for that is much simpler check than tearing apart the heater core.. at least as a first check.

-Christopher