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Unread 03-20-2012, 11:06 PM   #1
tilljo
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2006 KJ Liberty 
 
Join Date: Mar 2012
Location: Sonora, CA
Posts: 2
AC/Vent Problems!

My 2006 Jeep Liberty has problems with intermittant AC airflow. Sometimes I have the AC on with normal airflow and then at random times the air will almost stop flowing from the vents (The air often stays cold too). The odd thing is that I will still hear the air flowing inside the system, it just won't be coming out the vents anymore. It's like some door within the system closes randomly. When I redirect the air through the floor vents, or defrost etc, I notice that the slight airflow changes to those settings yet fails to come out the vents except for a slight amount. What could this be?

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Unread 03-21-2012, 12:49 AM   #2
socks
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2004 KJ Liberty 
 
Join Date: Mar 2008
Location: Richmond, Canada, British Columbia
Posts: 431
You might have a vacuum leak somewhere.
Or one of the vacuum hoses has come off of its mounts.
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Unread 03-22-2012, 02:48 PM   #3
JeepCares
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The heating-A/C system is a blend-air type system. The two blend-air doors control the amount of conditioned air that is allowed to flow through, or around, the heater core. This single zone heating-A/C system uses only one blend door actuator.

The A/C system is designed for the use of a non-CFC, R-134a refrigerant and uses an A/C evaporator to cool and dehumidify the incoming air prior to blending it with the heated air. A temperature control determines the discharge air temperature by operating the blend door actuator, which moves the blend-air doors. This allows an almost immediate control of the output air temperature of the system. The two mode door actuators operate the mode-air doors which direct the flow of the conditioned air out the various air outlets, depending on the mode selected. The recirculation door actuator operates the recirculation-air door which closes off the fresh air intake and recirculates the air already inside the vehicle. The blower motor controls the velocity of air flowing through the HVAC housing assembly by spinning the blower wheel within the HVAC housings at the selected speed by use of the blower motor resistor.


above information taken from service manual
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Unread 03-22-2012, 07:46 PM   #4
tilljo
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2006 KJ Liberty 
 
Join Date: Mar 2012
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Quote:
Originally Posted by JeepCares View Post
The two mode door actuators operate the mode-air doors which direct the flow of the conditioned air out the various air outlets, depending on the mode selected.
[/I]
How do the door actuators work? Are they run by vacuum or otherwise...?

Thanks for your input!
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Unread 03-23-2012, 07:40 AM   #5
JeepCares
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Quote:
Originally Posted by socks View Post
You might have a vacuum leak somewhere.
Or one of the vacuum hoses has come off of its mounts.
Quote:
Originally Posted by tilljo View Post
How do the door actuators work? Are they run by vacuum or otherwise...?
The heating-A/C system uses two vacuum operated mode door actuators (1) to control the movement of the mode-air doors within the HVAC housing.

When vacuum is supplied by the A/C-heater control to the vacuum connector (3) on one side of the defrost/floor actuator or the panel door actuator, the actuator rod is pulled into the actuator, which moves the mode door lever and mode-air door in one direction. When vacuum is supplied by the A/C-heater control to the other side of the actuator, the rod moves the mode-air door in the other direction.

The mode door actuators are retained to the HVAC housing by an integral mounting provision (2) and can be accessed for service from under the driver side of the instrument panel.

The mode door actuators cannot be adjusted or repaired must be replaced if found inoperative or damaged.
06-kj-heat-ac.jpg  
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Unread 07-14-2013, 12:35 PM   #6
DonaS12
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2005 KJ Liberty 
 
Join Date: Jul 2013
Location: Shallotte, NC
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Did you ever solve this AC airflow problem? I have a 2005 Liberty and I have had this problem for a while now, hoping to figure out the problem.
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Unread 07-14-2013, 05:00 PM   #7
streetglideok
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2005 KJ Liberty 
 
Join Date: Jul 2011
Location: Colorado Springs, Colorado
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Is it all the time, or is it intermittent? That can make a big difference on what it could be. It can be a mode door problem, or it could be an evaporator frosting over.
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Unread 07-15-2013, 08:41 AM   #8
rangerr47
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2012 KK Liberty 
 
Join Date: Aug 2011
Location: Dallas, Tx
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I just took my 2012 Liberty on its first long trip , Texas to NYC...The first day about half way through the day, this happened to me. I was pissed and really thought about calling off the trip, I must have AC...I turned it off for about 10min and then turned it back on and it was ok, it did this one more time later that day. Then for the rest of the trip it never did it again. It has never done this before, but Im usually only driving for maybe an hour tops.

Like he said, it will still be cold , but its like the vent is blocked, no air hardly comes out at all. And if you leave it on like this for a while, it will start blowing hot air and I could smell it getting hot, like electrical burning almost.

I have 5k left on my warranty so I was thinking about taking it in to be checked out.
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Unread 07-15-2013, 08:36 PM   #9
streetglideok
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2005 KJ Liberty 
 
Join Date: Jul 2011
Location: Colorado Springs, Colorado
Posts: 2,456
Sounds like a frosted over evaporator. If there is an undercharge of the a/c system, the evaporator will get colder than it is designed to, freezing the condensation on the evaporator. It'll build up to the point no air can pass thru it anymore. Only way to fix it is to have a full recovery and recharge of the system. Temporary fix is to turn off the a/c and leave the fan blowing on it. It'll eventually thaw out.
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