Typically, auto a/c units work better when a lower fan setting is used. The air flows more slowly through the evaporator and has more time to get colder. There is however, a mod that you can do that will make a difference.....if you want to go that far. You can get a high capacity accumulator/dryer with a site glass installed. This acomplishes two things. First, it allows for more moisture to be drawn out of the system, and allows for lower tempartures. Secondly, with the site glass installed, instead of using the factory recomendations to fill the system, simply fill it until all of the air bubbles are gone. Usually, you get 1/2 to 1 more pound in the system, which is not enough to cause damage, but is enough to help the cooling effect. Most foreign car companies have used site glasses for years and this is the factory procedure for filling the a/c system. I always put a good vacuum on mine for at least an hour, let it sit another hour to make sure there are no leaks, and then charge the system. It's always worked well for me. All this being said, the a/c in my Jeep works great. I wouldn't change a thing.

 

I have often wondered about that. It's hard to resist turning the fan up, though.

 

I've read many posts on here regarding reducing the heat coming through the hardtop. Some on this website have gone as far as painting the top of the hardtop white, some have put insulation on the inside.

I know on a very hot sunny day when I put my hand on the inside of the hardtop it's extremely HOT. Perhaps your problem is not the temp of the air in the vents, but rather the heat load is too great for the A/C to cool effectively.

I would suggest you measure the temp at the vents, and if the temp is too high take it in for warranty. Here are some posts related, I am sure there are more:

https://www.jk-forum.com/forums/show...ht=hot+hardtop

https://www.jk-forum.com/forums/show...oof+insulation

 

Top Off, Doors Off, sunscreen, and a bottle of water! Thats all I need!

S.R.

 

I've only had my JK for a month now but I have noticed an issue with the valve that controls the flow the heater core. When I drive my truck for a while and then let it sit for an hour or so, and then drive somewhere else; the vent blows hot air. I thought this might be residual from the sun heating the car so I tried it on lunch. (I work midnights) The Jeep actually blows hot air with the controls on cold and the A/C off. If I drive on the highway for about 20 minutes the air starts to cool off. When I first picked up the Jeep I thought the A/C was a little week but the next morning it was blowing ice cold so I blew it off. Now it never really cools down if I drive it around with lots of stops.
My guess is the heater valve is run off vacuum and when the engine is off; it lets the hot coolant heat up the core. The A/C evaporator is probably after the heater and it takes long to cool down the heater core on these 100+ days. Anyway my A/C blows really cold if the truck has sat over night. If your having problems with A/C not being cold; Turn the A/C off and the fan on and see if the air coming out of the vents is warm or warmer then it should be. If it is then you know tho look at the heater valve in the engine compartment.

 

There is something basically wrong with the JK air conditioning design. I have a hardtop. My wife's 03 TJ softtop cools MUCH BETTER. I do not know wether the coolant is under less pressure, there is less coolent specified, there is a different type of coolent in use, or the compressor location is bad. I just know the JK's air temp, as it leaves the vent, is no where near as cold as the TJ.
Yes, I can get the JK to cool down in 100 degree temp. It just is no where near as cool as our softtop TJ

 

The biggest problem is the radiant heat that comes thought the hard top. There is NO insulation to stop the sun from baking your brain. Get in your jeep and put your hand on the bottom of the hard top and see how hot it gets.

I will get a write up posted in the next week or so on a good solution.

 

My vents put out air in the high 20's to low 30's F when it is in the 90's outside.
It's enough to turn the vents away. Passengers in the back say it is cool enough, but deffinately not cold.
I think if a system is slightly lower performance, and the sun's rays are more intense than here in Maine, an owner could very well be experiencing higher cabin temps than I am. My Jeep A/C is nowhere near as effective as the one in my '02 Dakota was. That one would freeze a can of soda, no kidding.
edit to add: The A/C in my '02 VW Golf will freeze a soda, too.

RedneckJeep,

I tried your theory concerning fan speed and cool air from the vents.
Fan on low, the temp was about 35 F.
Each notch up in fan speed raised the air temp about 1 degree.
Each notch back down lowered the temp 1 degree.
This was repeatable many times, and it was as though the fan switch was doubling as a temp switch.
The higher air flow more than compensates for the degree reduction in temp.
The bottom line is, your explanation has been verified.

 

I'd say that it is a possibility something is wrong with it. I have run mine when it was upper 90's and 80% humidity, and it will keep me cool even with the doors off!

Yes... it did seem kind of silly to run the AC while wheeling with a bikini and tube doors, but I think all of us were running the AC that day.

 

Mine works very good had many days the official high was 95 and hotter. My temp gauge for outside air reads 100+ and after a few minutes I have to turn the AC vents away from me or get frozen.

I believe you have not enough coolant in ur system. evacuate check for leaks. if it holds vacuum, recharge.