A/C - Poor Performance/Compressor Cycles ON/OFF

Group Ref.: HVAC

Bulletin No.: 331221

Date: September, 1993

SUBJECT:
POOR A/C PERFORMANCE (DIAGNOSTIC PROCESS, REPLACE A/C COMPRESSOR LOW PRESSURE CUT OFF SWITCH)

MODELS:
1993 CHEVROLET CAMARO
1993 PONTIAC FIREBIRD

CONDITION:

Some customers may comment about inadequate A/C performance or intermittent A/C operation which may be accompanied by rapid cycling of A/C compressor.

CAUSE:

Faulty components or low refrigerant charge may cause comments of poor A/C performance or intermittent A/C compressor system operation.

CORRECTION:

1. All A/C system performance comments should be diagnosed utilizing Service Manual 1B1-10, "Insufficient Cooling Check" including initial check of ECM on board diagnostic system per Service Manual Section 6E3. The vehicle ECM does contain diagnostic codes for analysis of faulty A/C system components and low refrigerant charge. The ECM on board diagnostic system may also intermittently disable the A/C compressor as described in Service Manual Section 6E3.

2. If a potential refrigerant leak is indicated by the on board diagnostic system or A/C performance test, conduct leak testing according to the procedure described in the Service Manual Section 1B-5. Figure 1 in Section 1B-5 illustrates all A/C joints. Leak testing must be done at all A/C joints (including sensor/switch joints).



3. If a refrigerant leak is found at the A/C compressor low pressure cut off switch base, the switch may have been cracked due to over torquing. If necessary, replace the A/C compressor low pressure cut off switch with new P/N 10242579. Do not exceed new torque specification of 3 N-m (26.5 lb.in.). Current Service Manual specification of 6 N-m is incorrect. The "O" ring seal and the fitting for this joint should also be inspected for cuts/nicks per Service Manual procedure and replaced if necessary. Leak check should be repeated after re-assembly. Figure 1 in Section 1B-5 illustrates most refrigeration system components, including the low pressure cut off switch.

4. Vehicle should be road tested after diagnosis and correction of any conditions to assure proper A/C system operation. The ECM A/C performance diagnostic code (Code 61) will not set at vehicle idle; vehicle must be operated at road speeds for several minutes for the on board diagnostics to function.

PART AVAILABILITY:
Parts are currently available from GMSPO.

WARRANTY INFORMATION:

Labor Operation: T3370

Labor Time: 0.6 Hr.

Add to Recover and Recharge A/C: 0.7 Hr.