My 98 QC2500 4WD DSL with70,000 miles has air conditioning woes. I noticed a water puddle (larger than usual) underneath the pick-up where it usuall drips from the A/C drain. The problem is A/C was not selected w/dash switch. Also, the compressor iscycling 18 seconds on, 18seconds off. If dash switch is turned off the compressor will shut off. What is causing the pump to run? Would this create such a large amount of water in a short time? The dryer, condenser and lines erechanged out last spring(800$) due to corrision of the aluminum componets.I was suprise with this askeep it inside.I was toldto shut down theA/C( Not used much as I live in the Northwest) a few miles before reaching destination to allow a drying out periord. Any helpyou can offer will be appreciated,Thanks Bart [align=right][/align]

 

You probably had mode in recirc. or mix. That's why it's called air CONDITIONING it uses the A/C system to dry or condition the air so windows do not fog.

 

Also don't forget the A/C runs with the defroster. Usually if the compressor cycles on and off to quickly it is a sign that the system pressure is to low (probably a leak). I'm not sure what the usual cycle time is. Hopefully someone who knows will chime in. Not only shut it down early but run it in fan mode (no A/C) to help dry it out. Helps to keep the sytem from getting that mildew smell. Being doing that for years.