Hi. Got a 2001 CARAVAN SPORT with over 150000 miles and still going strong.No major problems here.Air conditioner began to do strange things.Of the three major AC vents in the center of the dash,only the right one blows cold air.Both center and left vents blow a somewhat warmer air.Not hot in any way,but less cold.Same thing happens with left vent(the one near the window),wich blows warmer air than the right one.Any help?

Two things come to mind:

1) Refrigerant level low
2) Mode control doors not operating properly.

I'd tend to lean toward 1), but before you go adding refrigerant, I'll add that:
a) you do NOT want to use anything from the parts store containing anything BUT pure R134a. Nothing that contains sealers of ANY type whatsoever. Typically, pure R134a is actually cheaper than the stuff that will literally murder your a/c system.

b) You need a manifold gauge set to monitor both the low/high side pressures at some ambient temperature and 1500 rpm if you go this route to make sure you're not creating problems.

c) The only "real" way to know how much refrigerant is in a system is to recover it and weigh it. Anything else is a guess.

So it'd be easiest to run the calibration sequence on the HVAC control unit - don't recall what the button sequence is, but its on the forum here somewhere. If that checks out, get or rent a manifold gauge set and try adding half a can (6 oz I think) while the a/c is running and monitor your vent temps. If the vents get substantially cooler, then you've probably found your problem. If not, stop and do not add any more.

If the temperature got cooler when you added 6 oz, the correct way to proceed would be to recover the charge, pull a vacuum on the system, and re-charge to the factory recommended amount. Otherwise, you can try adding a little refrigerant at a time while monitoring the vent temperature (preferably on a hot day) and stopping when the vent temps don't go down anymore with the addition of more refrigerant. You also need to watch your pressures so they don't go too high.

Chad

Would something like this work from Autozone instead of the actual manifold gauges? Quest / R134a Recharging Kit Smart Charge A/C Diagnostic Tool or is it just a toy type tool?
Steve