BLOWER MOTOR NOISE,CHIRP, OR SQUEAK(DIAG./REPL. MOTOR ASSY)

SUBJECT: BLOWER MOTOR NOISE - CHIRP OR SQUEAK

MODEL and YEAR: 1988-92 C/K TRUCKS

Some 1988-92 C/K trucks up to the provided vehicle identification breakpoints may experience a blower motor noise often described as a "chirp" or "squeak". The condition has been found to be caused by oil migrating via cooling air from the motor bushings to the commutator. As oil and brush material accumulate on the commutator, the motor begins to make noise.

This condition can be corrected by replacing the motor with a new blower motor assembly (P/N 52460703), which includes an internal shield to prevent oil from reaching the commutator. The assembly also includes the motor with the impeller already installed and balanced and should be used when replacing a motor for any reason.

Before replacing the blower motor assembly, be sure to check the module seams and joints for holes or gaps that may cause a noise mistaken for blower motor noise. For example, gaps in the seam between the scroll cage and the evaporator case are often misdiagnosed as blower motor noise.

Motors containing the oil shield can be identified by a date code stamped on the motor flange. The date code is the last four digits of the 13 digit number found on the motor flange. The first three numbers of the last four digits is the Julian date. The fourth or last digit is the year. Motors containing the air shield were first built on 0842 so motors with numbers higher than 084 contain the shield.

VIN BREAKPOINTS

Pontiac: 1GTDC14H8NE536476 1GCEC14K3NE191647

Fort Wayne: 1GTDC14H7NZ531097 1GCDC14Z8NZ192326

Oshawa: 2GTEC19K6N1541637 2GCEC19H6N1217107

Janesville: 1GKFK16K3NJ713709 (Suburban) 1GNEC16K9NJ327677

Janesville: 1GDL7H1T1NJ521177 (3500 HD) 1GBM7H1J9NJ105810

SERVICE PARTS INFORMATION

Part Number Description Quantity ----------- ----------- -------- 52460703 Blower Motor and Fan Assembly 1

Parts are currently available from GMSPO.

WARRANTY INFORMATION:

For vehicles repaired under warranty use: Labor Operation: D1320 Use applicable labor time guide for labor hours.

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.