on my 93 940 wagon, the driver side cable that operates the open/close/vent system had broken where it connected to the slider that runs along the lefthand rail.

Found a pair of cables at Voluparts in Atlanta, the only place I could find that parts out 940 sunroofs, voluparts@gmail.com, 888-280-4057. Bill even had the nasty clips that hold the sunroof headliner panel in place.

After replacing the cables (had to drop the headliner, sunroof & pan), I took the motor out and installed a manual crank. The crank allows me to feel what is happening and not apply enough torque to do damage again (the cable originally broke when I leaned on the motor switch too much).

Warning - if you live in a hot climate, do NOT service the sunroof - you'll roast alive. Wait until winter ....

And take LOTS of photos as you dis-assemble the sunroof - I couldn't find much detailed info available online about how things go together.

I would take the motor out and see if it cycles properly both ways - you could remove the motor, leaving it attached to the wires - it should cycle both ways and stop automatically.

If the motor works properly, then the problem is with the sunroof.

If the motor is bad, and it is the same as a 740, (you can close it with a phillips screwdriver) go to the junkyard and get a manual crank - I repaired 2 740s this way, 15 dollars instead of 350!

The manual crank works great - I do not understand why Volvo went to electric.

Have you read the FAQ? - several pages down, replacing the motor with a crank is spelled out.