UPDATE-ELECT. DIAGNOSIS OF C68 ELECT. A/C SYSTEMS

Model and Year: 1986-88 Y CAR

TO: ALL CHEVROLET DEALERS

*This is an update of the 1986 Corvette Service Manual Section 8A, page 64-1.

Entry into A/C diagnostics requires a C68 A/C control head with a rear defogger button. A substitute A/C control head with a rear defogger button may be used temporarily when entry into the A/C diagnostic mode is desired.

1987 and 1988 Corvette Service Manual Section 8A, pages 66-1 and 68-2 incorrectly describes entry into the Electronic (C68) A/C diagnostics. The correct procedure to enter the diagnostics is to press and hold the EXT TEMP button while pressing and then releasing the AUTO button.

For revised electrical diagnosis of C68 Electronic Air Conditioning Systems on 1986, 1987 and 1988 Corvettes substitute the diagnostic procedures with those in the 1989 Corvette Service Manual (ST-364-89). For the model year you are working on, refer to the electrical schematics.

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.