Q: Belt keeps slipping off

The possible causes of this include that the pulleys are not all in the same plane, the pulley on the harmonic balancer has shifted due to a break in the rubber bond, the belt tension is inadequate and/or the bearings on which the pulleys (or accessories) are mounted are worn or seized. To remedy this problem, a diagnostic is performed to figure out which parts have failed and need to be replaced. The belt will have to be removed (so all pulleys can be inspected) and replaced. Even if the existing belt can and will be reused the recommended service to request is a belt diagnostic/replacement and the responding certified mechanic will take it from there. This problem will be resolved very readily as the possible causes are limited in number.