My daughters have a 2002 Buick LeSabre. Today ONE windshield wiper stopped working. They said that it started making a noise, turned them off and then back on. Driver side works, but passenger side stays down. Could this be the motor or the arm assembly? or is that all the same thing?

SOURCE: windshield wiper

Check to see if the wiper motor moves the passenger side. If so, You may need to tighten the nut that connects the arm to the motor. Mine was stripped out because or snow & ice. So, I went to home depot and found a lock washer to fit.
Presto.... Nick from DE

SOURCE: 1999 Buick Century - passenger side power window does not work

Replace the Driver side window switch. These have a corrosion issue.

SOURCE: 2001 buick lesabre-ac problems

• Assumed your AC unit is OK, but uneven temperature distribution. Try to throw the heater on an off severtime. A sticky valve on the heater would cause similar problem.
  
• Observe the RPM while parking your car. While the AC cut in cut out (or turn on an off). If it cause no load on the engine. The freon may be low or the compressor is bad. In this case only the intake side of the evaporator is cooler than the other side.
  

SOURCE: when I start my 2003 buick lesabre the windshield

Behind your ignition inside the steering column, there is a plastic piece that screws to the back that has to do with your accessories. its bad or your wiper control stick also located on the steering column is bad.

SOURCE: 2002 Buick Lesabre drivers side window went down,

A couple of things to add to tinyp's solution. For Buicks, the regulator is bolted in, not riveted, which makes removal easier. Also, you'd better get used to this, as I have replaced 3 out of 4 window regulators on my 2002 LeSabre.