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-   -   Automatic Climate Control Question/Issue (http://www.jeepgarage.org/f203/automatic-climate-control-question-issue-16429.html)

rojpon74 12-18-2010 01:32 AM

Automatic Climate Control Question/Issue
 
Hi Everyone,

I have a strange issue with the automatic climate controls on my '02 WJ Overland. When I turn on the heater or front defroster in the mornings, it blows hot air for a while (30-45 minutes...I have a 1.5 hour commute) but then I notice the air starting to get cooler and cooler. If I shut off the system altogether and let it sit for a while, it'll blow hot air again when I turn it on and then cools down again after 30-45 minutes of use.

Is this sympotmatic of the infamous blend air door issue common on WJs with the automatic climate controls? If so, what is is the correct course of action?

FYI, in the summer, I have no issues when I use the A/C. It blows cold air all day long.

Thanks in advance for the help!

Frango100 12-18-2010 10:37 AM

Re: Automatic Climate Control Question/Issue
 
When you have hot air in the beginning and it gets cooler, then your blend doors are working fine. How is the inside car temperature when you feel the air coming out getting cooler? There are 2 infrared sensors on the control panel face, which measure the area temperature. If the area temperature is ok, the blend doors will be moved to keep the selected temperature, so the air coming out of the vents can/will become cooler, when the selected temperature is reached.

rojpon74 12-19-2010 11:27 AM

Re: Automatic Climate Control Question/Issue
 
The inside air temperature is warm, or at what it should be. Do the infrared sensors also work this way if the fan and mode selector are not set to "Auto?"

Quote:

Originally Posted by Frango100 (Post 319729)
When you have hot air in the beginning and it gets cooler, then your blend doors are working fine. How is the inside car temperature when you feel the air coming out getting cooler? There are 2 infrared sensors on the control panel face, which measure the area temperature. If the area temperature is ok, the blend doors will be moved to keep the selected temperature, so the air coming out of the vents can/will become cooler, when the selected temperature is reached.


Frango100 12-19-2010 04:49 PM

Re: Automatic Climate Control Question/Issue
 
In fact the infrared sensors don't measure the air temperature, here is how Jeep discribes it:
Dual infrared sensors mounted in the face of the control
unit independently measure the surface temperature
to maintain customer-perceived comfort temperature
under changing conditions.

It does not matter in which position the fan or mode switches are set, the infrared sensors are always used as one of the inputs to regulate the blend doors.

But when the temperature is at the required level, there should be no hot nor cold air coming from the air outlets, it should be somewhere in between, just to maintain the set temperature.

rojpon74 12-19-2010 06:32 PM

Re: Automatic Climate Control Question/Issue
 
Would the "in between" air temperature be perceivable? The air that comes out is noticeably cooler.

Quote:

Originally Posted by Frango100 (Post 320258)
But when the temperature is at the required level, there should be no hot nor cold air coming from the air outlets, it should be somewhere in between, just to maintain the set temperature.


Frango100 12-19-2010 08:59 PM

Re: Automatic Climate Control Question/Issue
 
The system is designed to keep a constant temperature in the cabin, so as long as this is achieved, the system is ok. You can only raise the vent air temperature again by selecting a higher temperature for the respective zone.

rojpon74 12-19-2010 10:09 PM

Re: Automatic Climate Control Question/Issue
 
Good deal. So, it sounds like it's working correctly. Thanks!

Quote:

Originally Posted by Frango100 (Post 320387)
The system is designed to keep a constant temperature in the cabin, so as long as this is achieved, the system is ok. You can only raise the vent air temperature again by selecting a higher temperature for the respective zone.



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