ROUGH IDLE OR VIBRATION COOLING FAN INFORMATION

VEHICLES AFFECTED: 1985 Cadillac 'C' Models

When diagnosing vibrations which may occur primarily at idle or an apparent rough idle condition on a 1985 FWD Fleetwood or Deville, the cooling fans should be checked as a possible source of the disturbance. This can be done by entering diagnostics and using the cooling fans override to activate the fans with the engine off. If the vibration is attributed to the cooling fans, disconnect one to determine which is the source.

If the fans are found to be the cause of the roughness, this is most likely due to improper mounting or an excessive amount of some foreign material, such as rustproofing stuck on one or more of the blades causing an imbalance condition. Prior to any parts replacement, inspect mounting and fans since even a small imbalance on a fan blade can cause appreciable vibration.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.