Heater problems, PLEASE HELP!

[LibertyJay]

Hello everyone, happy winter. My wife has a 2008 kk and we are having problems with the heater. It blows cold on the driver side however it is warm on the passenger side. I have checked the coolant level and it was slightly low so I added some more and that didn't do anything. I removed and sprayed the blend door actuator with wd 40 and that seemed to help a little but now it is cold again. Today I bought and installed a new actuator and the passenger side is a little warmer but still no luck on the driver side. The driver side floor vents and vent by the door are the coolest. I checked the temperature of the radiator hoses going into the firewall and one was at about 150 the other was approximately 125. Inside the passenger vents blew at about 107 to 112 and the driver side blows at about 60 to 80 degrees. Does anyone have any idea? Driving with cold feet sure isn't fun . Thanks in advance.

 

[dude1116]

Hello everyone, happy winter. My wife has a 2008 kk and we are having problems with the heater. It blows cold on the driver side however it is warm on the passenger side. I have checked the coolant level and it was slightly low so I added some more and that didn't do anything. I removed and sprayed the blend door actuator with wd 40 and that seemed to help a little but now it is cold again. Today I bought and installed a new actuator and the passenger side is a little warmer but still no luck on the driver side. The driver side floor vents and vent by the door are the coolest. I checked the temperature of the radiator hoses going into the firewall and one was at about 150 the other was approximately 125. Inside the passenger vents blew at about 107 to 112 and the driver side blows at about 60 to 80 degrees. Does anyone have any idea? Driving with cold feet sure isn't fun . Thanks in advance.

Clogged heater core? That's the next thing I would check. Flush it out with water.

 

[LibertyTC]

I think u were on to something re the actuator. Unfortunately I dont have a KK FSM as Im a KJ guy, but hopefully someone more familiar with the KK or that has a manual can chime in soon.
It more sounds like on one side, the actuator or even blend door may not be working right.
This can be related to something stuck, a vacuum leak on one of the hoses, or the blend door that needs oiling LOL I wonder how many actuators are in there?

 

[LibertyJay]

Thanks for the advice, hey dude, I have tried to remove the hoses from the heater core at the firewall and was able to loosen the hose clamps however I couldn't detach the hose and I didn't want to pull too hard and risk breaking something. The only other way I can think of is to detach the hoses from the radiator however it appears that the air box must be removed first and I can't see how to do that. Any further advice you can lend?

 

[dude1116]

Looks like those are your only two ways. Looks like the air box doesn't need to move for the KJ to get to the lower hoses...but according to this video those are a pain to get to.

2003 Jeep Liberty 3.7L Flushing the Heater Core - YouTube

See if that helps!

 

[LibertyJay]

I don't know about the air box in the kj, but ours is an 08, so it is a kk...

 

[dude1116]

Right. Just commenting what I actually know about. Airboxes are usually pretty easy to remove.

 

[LibertyJay]

Yeah, I may have to take another look at the air box...

 

[streetglideok]

I checked the temperature of the radiator hoses going into the firewall and one was at about 150 the other was approximately 125.

That's all you need right there. Heater core is partially obstructed. There should be no difference in temperature between the inlet hose and outlet hose of the heater core. Chances are, its full of slime. I've had a few KKs come in lately with poor heat issues similar to yours. Sadly, you must evac the a/c system and pull the dash back to access the hvac case. It has to come out, then separate the heater core box from the rest of the hvac case to remove.

 

[LibertyJay]

Hey street thanks for the input. I wasn't sure if there was supposed to be any heat loss through the heater core. But if you say that you have seen that issue with others then I guess that should be my next course if action. It's it possible that a heater core flush might be sufficient to cure this problem, as that would probably be easier. If so, how can I safely disconnect the hoses from the heater core at the fire wall. I have removed the house claps but the hoses seem to be stuck on and I didn't want to pull to hard and damage something.

 

[streetglideok]

You can attempt to backflush it with a diluted solution of CLR. Last one we dealt with, it wouldn't remove the slime in the core. One of the issues you will have, is this is a single pass design, and instead of forcing slime or debris out, it will merely flow thru the path of least resistance. If you can get a hose removal pick, you can use it to try and free the hoses, as they are likely stuck. Sometimes if you can squirt a little WD40 under the edge of the hose, it will work around and loosen the hose.

 

[MarkJ]

Heater core is just a small radiator. It RADIATEs heat into the airstream going through the heater. Otherwise you would have no heat. Of course one hose is going to be measurably cooler than the other when it is working right. Not sure exactly how much...point is: measure temp on a working heater (hopefully similar model) before tearing everything apart.
Mark