I have a 92 Previa that's in good shape. The only thing that's not working is the rear sunroof. When I push the switch to open it I can hear the motor run. It sounds like it runs smooth and without a load but the roof does not move. Last year I took some of the vents off the rear air conditioner but when it looked like I would have to remove the rear AC I just put it all back together. Anyone had this problem and know what it might be and what if the rear ac must be removed to fix the roof? Thanks for any help...