ncjksu_1967

I have a 2009 JKU that now doesn't want to blow hot air from the vents. I've recently installed a Mishimoto radiator and thermostat. I've flushed the heater core twice in the last two weeks and I'm still not getting hot air from the driver side vents or defroster. It all works okay (but not like it should) if I have the air on recycle, but if I use normal air or switch from vents to defroster and back to vents again...I get cool air out of the driver side vents.

All the signs lead me to believe it's not the heater core, but I'm at wits end trying to figure out what it can be. I don't have a sweet smell when the air is blowing, I don't get a fog in the cabin of the jeep, I dont' have wet floor mats and my heater hoses are super hot to the touch after running the jeep. I've checked the blend door and I've seen it move/rotate when I changed the air from hot to cold, so I'm thinking that that's not it either. Can someone please help...?

ronjenx

You can actually see the blend door?

ncjksu_1967

Yes, I contorted myself got up under the dash enough that with a flashlight in one hand and my other hand reaching up to the temperature knob, as I turned the temp from hot to cold, I could see the blend door rotate from vertical to horizontal. It wasn't easy and it didn't feel that great on my back, but I was just glad that I didn't have to remove the entire dash to see it.

ronjenx

I guess I'll have to look again on mine, because all I can see are the levers, not the door itself.
(Working under the dash was so easy on my first few cars. Now, it's )

ncjksu_1967

Now you have me thinking if what I saw was in fact the blend door or another part! What I saw was a white piece of plastic shaped like an elongated diamond, and it was located on the drivers side of the center console...when you turn the temp knob, it would rotate from vertical to horizontal based on if it was cold or hot. If that's not the blend door, then the guy who posted a video on youtube that I saw the other day, the guy who posted it called it the wrong part.

If that is not the blend door, then I apologize. I usually don't work on my jeep until now, so I honestly only know what I can find that others have posted online. That's why I decided to come on this site and hopefully get some help with what is going on with my jeep.

ronjenx

I can see the white plastic levers move when I twist the temp dial.

Where I was going with my questions is...
Seeing the levers move doesn't verify the door inside is moving.

There have been quite a few temperature control threads dealing with blend doors not moving, or broken doors where only part of it moves.

JKZinger

If your getting cold air it is more than likely the heater core. They replaced mine under warranty 4 years ago and I got hot air again and had worked since. Casting sand issue.

GileadGarage

Slight change in plans here...

I am bringing it in to local shop to flush the cooling system. They have a flush machine and I will have them do it twice, once with distilled water, then refill with mopar coolant.

I will then back flush heater core with warm vinegar solution through a pump. I am rigging up a pump system with a 15psi bypass relief and a screen filter and will leave it on for like 8 hrs.

I just do not have the time around this stressful Holiday season to replace everything, and I do not want to replace the core alone only to have it plug again if I do not replace everything else. In the future I will likely need to replace everything but would like to get through the winter. In the Summer I have other vehicles I can drive so my wife can use my car and I can take my time with it.

This is todays plan anyway, we'll see how it goes tomorrow at the shop. I am anxious to see what comes out of the cooling system. If I do need to replace the core I am not too worried about using this procedure. The dealer should make a kit to do it this way. So dumb to do it the way they do....

Thanks,

Mark

Reptillian

posted to wrong thread, apologizes

on_order

Same issue here - i was hoping to not have to change the heater core in single digit weather :/