A/C PRESSURE CYCLING SWITCH 'CLICKING' NOISE

VEHICLES AFFECTED: 1988 C/K MODELS W/AIR CONDITIONING

Some 1988 C/K trucks have experienced an A/C pressure cycling switch "clicking" sound. This condition exists when compressor operation is needed, such as A/C or defrost. The condition is inherent to the switch's design and its location on the A/C accumulator "J" pipe (See Figure 1).

The service procedure and parts required to address this condition are as follows:

NOTE: This procedure will significantly reduce the "clicking" sound, but may not eliminate it completely in all cases.

PARTS INFORMATION

DESCRIPTION PART NUMBER ----------- ----------- A/C Pressure Cycling Switch 3096605 Jumper Wire 12058652

SERVICE PROCEDURE

1. Disconnect A/C pressure switch wire from A/C pressure cycling switch. This can be accomplished by depressing indentations on electrical connector and pulling.

2. Unscrew old A/C pressure cycling switch from A/C accumulator "J" pipe schrader valve and replace with new 1989 switch (P/N 3096605).

There is a distinct physical difference between the new 1989 pressure cycling switch (P/N 3096605) and the old 1988 pressure cycling switch (P/N 3040500).

The new 1989 switch is approximately 1/2 the size of the 1988 switch. The male connector end of 1988 switch is visible where as the 1989 male end is contained in a black plastic housing and is not easily visible. Both the 1988 and the 1989 pressure cycling switches have visible part numbers stamped on them.

3. Open wire conduit containing old pressure cycling switch wires midway into conduit. Cut the two wires. (Off-set cutting is recommended to allow proper fit when reinstalling wires and connectors into conduit. See Figure 1)

4. Strip back all wires and splice new jumper wire (P/N 12058652), using 2 wire connectors (size 16-14). Due to 1989 pressure cycling switch design, the current 1988 electrical connector will not fit and, therefore, must be replaced with new jumper wire. The white wires from the new jumper wire can be connected to either green wire from old connector wire.

NOTE: The use of shrink wrap or electrical tape around connectors is recommended to prevent moisture intrusion and wire separation.

5. Reinstall wires into conduit and tape end.

6. Plug new jumper wire connector into new A/C pressure cycling switch.

7. Test circuit and check for proper operation.

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.