REDUCED A/C PERFORMANCE (DIAG./REPLACE LIQUID LINE)

SUBJECT: REDUCED A/C PERFORMANCE (PERFORM DIAGNOSTICS/ REPLACE LIQUID LINES)

VEHICLES AFFECTED: 1991 "B" CAR AND SOME 1992 ROADMASTERS

Application: 1991 "B" Styles between VIN Breakpoints Below and Some 1992 Roadmasters.

Chevrolet - From MR124639 To MR149912 MW234399 To MW258877

Buick - From NR400911 To NR419101 MW401829 To MW406551

Oldsmobile - From MW304592 To MW307085

Condition:

---------- Some vehicles built between the above listed VIN breakpoints may exhibit reduced A/C performance. This condition will be indicated by a 10 degree temperature increase at the centre duct and a low side pressure that will not reach the 24 PSIG compressor cycle "off" point.

Cause:

------ The liquid line may be oversized at the location of the orifice tube, allowing refrigerant to "bypass" the orifice tube.

Correction:

----------- The technician should perform the "poor performance diagnostics" as outlined in the Service manual. If the performance is not improved when following the guidelines, Replace the Liquid Line.

For vehicles being repaired under warranty use: Labour D3083

Labour Time 1.0 Hours

NOTE: Time includes recover/recharge A/C system.

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.