I am having a problem with the air conditioner in my 03 TJ. When I turn on the ac, the air blows cool, but only through the floor vents and the defroster vent. I rotate the knob from recirculate, dash vents and dash vent/floor with no change. When I try just the vent function without the compressor I get the same. Any suggestions?

I will take a stab at this based on other vehicles.

The control of the ventilation doors is USUALLY controlled by vacuum. My guess is that you have a loose or broken line that is preventing that system from working.

Thanks Jim. I will have to get under the dash to take a look. After I posted issue, I was expecting to come back and find all sorts of answers such as What is AC, run topless, pull the doors, disconnect the ac stuff and plumb for air, etc.

Thanks for the straight answer.

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The first place to look is under the hood at the firewall. If it is a vac problem usually it will be found there. You should have ONE nipple about in the center of the firewall with a vac hose going to it. Follow the hose and make sure it is intact and the fitting it gets it's vac from is intact.
I wrote about in the center... that's where the older models are, perhaps they have moved the nipple somewhere else on the firewall. In any case there should only be one nipple thru the firewall.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

It's pretty common for the vacuum supply hose nipple on the intake manifold to loosen and pull off the intake manifold on the 4.0l, check to make sure it's still connected. If it came off, use a zip tie to tighten the rubber boot and help keep it in place.

There also is a vaccum reservior for the heater system, under the battery tray, IIRC. Sometimes the plastic supply hoses to and from it get eaten by spilled battery acid. If there's a pinhole or crack in it, the system won't work.

Lastly, if all the vacuum hoses uder the hood check out, the vacuum control switch on the heater control itself may be bad. The heater control can be removed and the lines tested with a hand held vacuum pump and some plugs. If the vacuum control switch is bad, you may hear some vacuum leaks coming from inside the heater control head.

Hope this helps!

Thanks guys. I will look for the nipple on the firewall and check the vac lines for the AC.

The funny thing is I never use it, preferring to run with just a safari top. The wife on the other hand wants me to put the windows/doors on and use the AC.

The vac line going into the nipple was bad. Couple of wraps with black tape and the temp fix is good.

Thanks for the assist.