I have a 98 Cadillac STS and the drivers side.

Measure the voltage on the wires at the window motor. You should find 12 volts on them when pressing either switch, just the polarity will change. If you do find voltage in the "up" direction, the glass is sluggish in the tracks. If you do not find voltage going up, most likely there is a Body Computer involved in the power window circuit. As with all circuits that have been needlessly complicated by adding an unnecessary computer, the window switch no longer switches current to the motor directly. That was too reliable. With the Body Computer, the computer does the switching after getting an input from the switch. One potential clue is the switch will only have three wires instead of four, although the wires for the other windows can make counting them confusing. With the older, more reliable systems, two wires go from the switch directly to the window motor. On computer-controlled systems, the wires at the switch can be smaller in diameter, and the motor wires will go right into the harness that goes through the door hinges. If you have that newer system, don't overlook the possibility of a broken wire between the hinges.

If you do not find voltage at the motor in the "up" position, you can temporarily switch the two wires in the connector or just jump them with a pair of small jumper wires to run the window up when you press the "down" button. If there is voltage there in the "up" position, push on the bottom of the glass to help it up. If that works, spray the rubber tracks with Silicone Spray Lube. That goes on like water, evaporates, and leaves a film of "slippery" behind. Works great on sluggish seat belts too when they stick on the upper anchors.