You need a new window regulator.

 

thanks so much for the information

 

740's and 840's have a known issue with regulators; particularly the driver's since it is used most frequently. Pulling the door panel is easier than most cars. Early models had the regulator held in with 4 bolts which made exchanging simple but by 91, they began using pop rivets. This means the old rivets need to be drilled out to remove and a pop rivet tool used to install the new one. In a pinch, it is possible to use bolts by inserting them from the back side of the regulator and then bolting the regulator down with nuts from the outside. Somewhat of a pain...but I've done it once.

 

Your regulator itself may be fine. Most likely you just have the plastic sliders that attach the glass to the regulator broken.

 

If the motor is working but the glass is not moving -- it sounds like the glass has come off the track. There is a rubber strip that nests the glass into the track. In other words, glass is connected to the track by friction. This rubber strip (Volvo calls is Filler Strip, # 13 here) disintegrates and glass comes loose.

If the filler strip is the culprit, you need to get a new one. Tasca sells them for $ 18. Let us know how this goes.

 

Most likely it's the Sliding Block(s), #11 in the drawing. These little little plastic things break a lot.