For 1990-2009 cars

# MOAN OR VIBRATION WITH A/C RUNNING

1988-89 F AND 1989 B W/5.0L, 5.7L

Some 1988 and early 89 F-cars and early 1989 B-cars equipped with 5.0L or 5.7L engines (with serpentine accessory drive) may exhibit a moan or engine vibration when the air conditioning compressor is engaged. This condition may be corrected by the "installation of a support brace to the A/C compressor mounting bracket.

Applicable part numbers are listed in the table below:

#### LO3 89 B and 88-89 F

QTY P/N PART NAME ---- ---- ---------- 1 10055888 Stud, A/C compressor 1 14100808 Stud, Intake manifold 1 10105289 Brace 2 14057004 Nut

#### LB9 and L98 88-89 F

QTY P/N PART NAME --- ---- --------- 1 10055888 Stud, A/C compressor 1 11508476 Bolt, Intake manifold 1 10105292 Brace 1 14057004 Nut

#### Service Procedure:

#### LO3 Applications:

1. Disconnect the negative battery cable.

2. Remove inboard A/C compressor bolt and install the longer of the two supplied studs, P/N 10055888 as shown in Illustration 1. Torque to 40-60 N.m.

3. On B-car applications, remove fuel line clamp attaching bolt as shown in Illustration 1.

4. Install the shorter of the two supplied studs, P/N 14100808 in the intake manifold boss as shown in Illustration 1. Torque to 20-30 N.m. (On B-car applications, bolt was removed from this hole in step 3. On F-car applications this hole is currently unused).

5. Install brace P/N 10105289 supplied as shown in Illustration 1 (slotted end inboard) using two P/N 14057004 nuts. Torque to 26-40 N.m.

6. Reconnect the negative battery cable.

#### B9 and L98 Applications:

1. Disconnect the negative battery cable.

2. Remove inboard A/C compressor bolt and install supplied stud P/N 10055888 as shown in Illustration 2. Torque to 40-60 N.m.

3. Install brace P/N 10105292 supplied as shown in Illustration 2 (slotted end inboard). Attach the inboard end of the brace to the lower of the two open threaded holes located on the intake manifold just below the IAC motor using supplied bolt P/N 10508476. Torque to 16-24 N.m. Attach the outboard end of the brace onto the stud installed in step 2 using P/N 14057004 nut supplied. Torque to 26-40 N.m.

4. Reconnect the negative battery cable.

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.