[RIP]

Two areas to look at: the ventilation system and the A/C compressor clutch.

I know this applies to 96-99 vans. Not sure about 01. The ventilation system has a self test feature. You can turn the ignition switch to "on" or start the van. Hold the top and bottom wiper buttons in for a few seconds. You'll see a series of lights flash on the ventilation push buttons and hear vent door actuators moving under the dash. After 20-30 seconds, you should only see a slow flash from the upper wiper button. Unfortunately, I don't know what it means when any other particular button is flashing at the end of the test. I've checked many websites and this forum for the meanings but, can't find it. For now I would concider any failure indication as a bad blend door actuator.

Is the clutch engaging on the compressor? Watch the compressor when someone turns on the A/C. The ring outboard of the pully/belt should start to rotate. If it doesn't, use a meter to check for 12 volts DC at the connector at the compressor. If it's not there you'll have to go backwards with the meter and find the problem. There is a relay on the power distribution panel that applies power to the clutch. Are the fuses good?

If the clutch is engaing I would have a pro check to make sure all the system pressures are correct.