AC running in defog/floor mode.

[MarkJ]

I am used to running in the defog/floor mode in all my cars when the weather is typical. Rain or fairly cold. Just seems like a good compromise for me. Up till now, cars I own have all added the AC to the defog only (or max defog) setting. I would love to find a way to defeat this option so that the AC would only turn on in the max defog setting.
Looks like this is controlled in the PCM and not something that is possible to change? Can the PCM be re-programmed?

 

[cplchris]

I don't know whether it is controlled by the pcm or just the ac/heat control unit (ac knobs). the a/c does come on automatically once you turn the mode knob past the floor position. here are possible override solutions:

if controlled by the ac/heat control unit only (not by PCM):

purchase another unit and tear into and eliminate the connection between the vent position knob and the a/c on/off control.

if controlled by pcm (would also work for the above possibility):

install an a/c kill switch

reasons to leave it alone:

the purpose of the a/c running on floor mode or higher is to keep moisture out of the jeep, which is obviously a good thing.

during the winter it is good to run the a/c. not running it and allowing the refrigerant to circulate will cause seals to fail prematurely.

so the best advice I have is to leave it alone.

 

[LibertyTC]

I like the fact that the AC runs in both floor & defrost settings.
Two benefits, one it dries the air inside the KJ and on windshield.
Second is that the AC compressor runs in these settings, keeping the system working.
Not using the AC/compressor for prolonged periods will cause problems down the road.

 

[MarkJ]

I checked the wire diagram and didn't see a way to change it so I suppose I am stuck. I am aware that you have to run the AC now and then to lube and keep seals fresh. Just didn't want it running 24x7 when I don't need it. It doesn't have to run all the time. On my other cars I rarely need it to defog the windshield, usually just running straight heat on low defog/floor takes care of it 90% of the time. Not good for mileage either. Sigh.

 

[tommudd]

The system is built to operate a certain way, its a good system and does what its suppose to do
As far as mileage goes, a 100 mile trip may take a pint more ( more than likely even less) , not a huge amount of savings

 

[MarkJ]

Then I best stop fretting! Habit is a strong thing...

 

[tommudd]

Then I best stop fretting! Habit is a strong thing...

I hate power windows, power mirrors, ABS ( Thankfully mine doesn't have it) traction control, hill descent and a host of other modern " conveniences" but anymore you have to live with them! :shrug::icon_lol: One reason I refuse to buy a new vehicle

 

[tjkj2002]

I am used to running in the defog/floor mode in all my cars when the weather is typical. Rain or fairly cold. Just seems like a good compromise for me. Up till now, cars I own have all added the AC to the defog only (or max defog) setting. I would love to find a way to defeat this option so that the AC would only turn on in the max defog setting.
Looks like this is controlled in the PCM and not something that is possible to change? Can the PCM be re-programmed?

Normal operation as is on all newer vehicles.




If I run "auto mode" in my '03 Town Car the AC is on 100% of the time regardless of what temp I set it to.

 

[flair1111]

there is a thread here somewhere that tells you how to go around this and the AC will only work if you push the ac button on i think the 04-07 models. either way ive had mine bypass the AC like this for years with no problems. all one needs to keep in mind is to be sure to run the AC every few days to keep the oil in the system circulated and all the parts lubed.

i took out my heater/ac dials and opened the back and basically glued on a very thin piece of plastic over a few of the circuits. this way when you turn the selector dial, the ac contacts dont get touched, therefore no ac on any setting unless you actually press the ac button. mines been this way since 2007 and zero problems. all your doing is just blocking contact with the ac circuit when the dial is spun around to the last few positions.

let me see if i can find that thread.

EDIT; i cannot locate the thread. maybe someone here can find it, but its here somewhere unless its been taken down.

 

[uss2defiant]

idk
this?
http://www.jeepkj.com/forum/f202/how-modify-your-c-heater-control-26491/

 

[MarkJ]

idk
this?
http://www.jeepkj.com/forum/f202/how-modify-your-c-heater-control-26491/

Hot Damn! Just what I was looking for. I have to read it further and slower but a couple posts in they were modifying the area I am interested in.
Thanks!
Mark

 

[uss2defiant]

use google to search the forum. A lot better.
do this

search phrase site:www.jeepkj.com

 

[flair1111]

idk
this?
http://www.jeepkj.com/forum/f202/how-modify-your-c-heater-control-26491/

yes thats it a few posts into it. ty for finding it. i saw that thread but forgot it didnt address the issue until a little bit into it. read a few posts down and its there.

EDIT: i used a piece of plastic about 1/64" thick and glued it in place over said contacts. its literally been since 2007....no problems. works very very good!!