UNDERHOOD MOANING NOISE KINKED AIR CHECK VALVE HOSE

VEHICLES AFFECTED: 1985 (RWD) Fleetwood Brougham

Some 1985 Fleetwood Broughams built before VIN broadcast number 003500 may experience a low pitched moaning noise during closed loop driving conditions This condition may be caused by a restriction in the air hose which connects the AIR control valve and the catalytic converter AIR check valve, resulting in a resonance in the hose. The restriction may be caused by excess hose length which results in a kink at the performed bend in the hose. If a kinked hose contacts the air conditioner evaporator housing, the noise is amplified and conducted into the passenger compartment of the vehicle.

To verify this condition, inspect the catalytic converter AIR check valve hose. Look for either a kink at the preformed bend of the hose and/or the hose contacting the air conditioner evaporator (see Figure 1). If the AIR hose is found to be kinked and/or contacting the air conditioner evaporator housing, follow the procedure described below.

1. Remove the two plastic hose clamps from the air hose which connects the AIR control valve and the catalytic converter AIR check valve.

2. Remove the air hose.

3. The correct length of the air hose, with the preformed bend held straight, is 6-1/4 inches. Using a knife or razor blade, cut the AIR control valve end of the air hose to 6-1/4 inches (see Figure 2).

4. Install the hose on the vehicle being sure the hose is seated completely onto both the AIR control valve and the catalytic converter check valve.

5. Check for kink in the air hose. If a kink is still present, remove the air hose and trim enough hose from the previously cut end to remove the kink. Reinstall the air hose on the vehicle.

6. Reinstall the two plastic hose clamps.

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.