D: A/C DOES NOT OPERATE
PINPOINT TEST D: A/C DOES NOT OPERATED1 CHECK A/C CLUTCH OPERATION
- Prepare vehicle as follows:
- Set A/C control at MAX A/C.
- Run engine at approximately 1500 rpm.
- Does A/C clutch operate?
- Yes
Go to D2.
- No
Go to D6.
D2 CHECK VOLTAGE SUPPLY AT SWITCH
- Turn engine off. Leave ignition switch in RUN position.
- Using a test lamp, check for voltage at Pin C Circuit 294 (W/LB) at A/C damper door switch
- Did test lamp illuminate?
- Yes
Go to D5.
- No
Go to D3.
D3 CHECK VOLTAGE SUPPLY TO SWITCH
- Using test lamp, check voltage at output side of Fuse 10 (15A).
- Did test lamp illuminate?
- Yes
Service Circuit 294 (W/LB) for open circuit. Restore vehicle. Retest system.
- No
Go to D4.
D4 CHECK CIRCUIT 296(W) FOR SHORT
- Using an ohmmeter, connect one lead to output side of Fuse 10 (15A). Connect second lead to a known good ground.
- Disconnect A/C damper door switch.
- Is resistance five ohms or less?
- Yes
Service Circuit 294 (W/LB) for short to ground. Replace Fuse 10 (15A). Restore vehicle. Retest system.
- No
Go to D5.
D5 CHECK A/C, HEATER CONTROL SWITCH
- Reconnect A/C damper door switch
- Using a test lamp, check voltage at Pin 10 Circuit 348 (P).
- Did test lamp illuminate?
- Yes
Go to D6.
- No
Replace A/C damper door switch. Restore vehicle. Retest system.
D6 CHECK A/C CYCLING SWITCH
- Disconnect A/C cycling switch.
- Start engine, A/C should be in MAX A/C mode.
- Using a jumper wire, connect one end to Pin 1 at A/C cycling switch connector. Connect second lead to Pin 2 at A/C cycling switch.
- Observe A/C dutch.
- Did A/C clutch engage?
- Yes
Replace A/C cycling switch. Do not discharge system. A/C cycling switch has a Schrader valve. Restore vehicle. Retest system.
- No
Go to D7.
D7 CHECK VOLTAGE OUTPUT FROM A/C PRESSURE CUT-OFF SWITCH
- Turn engine OFF, leave ignition switch ON. Gain access to A/C pressure cut-off switch as outlined.
- Using test lamp, check Pin 1 Circuit 198 (DG/O) at A/C pressure cut-off switch connector for voltage.
Did test lamp illuminate?
- Yes
Go to D8.
- No
Service Circuit 198 (DG/O) for open circuit. Restore vehicle. Retest system.
D8 CHECK VOLTAGE INPUT TO A/C PRESSURE SWITCH
- Using test lamp, check Pin 2 Circuit 883 (PK/LB) for voltage at A/C pressure cut-off switch.
- Did test lamp illuminate?
- Yes
Go to D9.
- No
Replace A/C pressure cut-off switch. Restore vehicle. Retest system.
D9 CHECK SUPPLY TO A/C COMPRESSOR CLUTCH CONTROL RELAY
- Using a test lamp, check Circuit 198 (DG/O) at A/C compressor clutch control relay connector.
- Did test lamp illuminate?
- Yes
Go to D10
- No
Service Circuit 198 (DG/O) for open circuit.
D10 CHECK VOLTAGE FROM A/C COMPRESSOR CLUTCH CONTROL RELAY
- Using a test lamp, check Circuit 347 (BK/Y) at A/C compressor clutch control relay connector.
- Did test lamp illuminate?
- Yes
Go to D16.
- No
Go to D11.
D11 CHECK VOLTAGE AT POWERTRAIN CONTROL MODULE (PCM)
- Using a test lamp, check Circuit 198 (DG/O) at powertrain control module Pin 10 for voltage.
- Did test lamp illuminate?
- Yes
Go to D12.
- No
Service Circuit 198 (DG/O) for open circuit. Restore vehicle. Retest system.
D12 CHECK VOLTAGE OUTPUT FROM POWERTRAIN CONTROL MODULE (PCM)
- Using a test lamp, check Circuit 361(R) at powertrain control module Pin 57 for voltage output.
- Did test lamp illuminate?
- Yes
Go to D13.
- No
Refer to Powertrain Management/Computers and Control Systems/Testing and Inspection for additional information. Testing and Inspection
D13 CHECK GROUND CIRCUIT FROM POWERTRAIN CONTROL MODULE (PCM)
- Using a test lamp connected to a known B+ supply, check circuit 73 (0/LB) at powertrain control module Pin 54.
- Did test lamp illuminate?
- Yes
Go to D14.
- No
Refer to Powertrain Management/Computers and Control Systems/Testing and Inspection for additional information. Testing and Inspection
D14 CHECK POWERTRAIN CONTROL MODULE (PCM) GROUND AT A/C COMPRESSOR CLUTCH CONTROL RELAY
- Using a test lamp connected to a known B+ supply, check Circuit 73 (0/LB) at A/C compressor clutch control relay connector.
- Did test lamp illuminate?
- Yes
Replace A/C compressor clutch control relay. Restore vehicle. Retest system.
- No
Service Circuit 73 (0/LB) for open circuit. Restore vehicle. Retest system. Go to D15.
D15 CHECK SUPPLY TO A/C CLUTCH
- Disconnect A/C clutch
- Using a test lamp connected to a known good ground, check Circuit 347 (BK/Y) at A/C clutch connector.
- Did test lamp illuminate?
- Yes
Go to D16.
- No
Service Circuit 347 (BK/Y) for open circuit.
D16 CHECK A/C CLUTCH GROUND CIRCUIT
- Using an ohmmeter connected to ground, connect second lead to Circuit 57 (BK) at A/C clutch connector.
- Measure resistance.
- Is resistance 5 ohms or less?
- Yes
Replace A/C clutch. Restore vehicle. Retest system.
- No
Service Circuit 57 (B/K) for open circuit. Restore vehicle. Retest system.
D17 CHECK A/C CLUTCH CYCLING
- Use refrigerant system pressure/clutch cycle rate and timing evaluation charts.
- Prepare vehicle as follows:
- Hook up manifold gauge set. Set A/C control at MAX A/C.
- Set heater blower motor switch on HIGH.
- Set A/C control to full COLD.
- Close fuel filler doors and windows.
- Use a thermostat to check temperature at center discharge register; record outside temperature.
- Run engine at approximately 1500 rpm with A/C clutch engaged.
- Stabilize with above conditions for 10-15 minutes.
- Check A/C clutch OFF/ON time with watch.
- Did A/C compressor cycle very rapidly?
- Yes
Go to D18.
- No
Go to D19.
D18 RECHECK A/C CLUTCH CYCLING SWITCH
- Using a jumper wire, bypass A/C cycling switch.
NOTE: You must have sensitive hands for this procedure.
- Hand feel A/C evaporator inlet and outlet tubes.
- Is outlet tube approximately same temperature between -2°C and 4°C (28°F to 40°F) or slightly colder than inlet tube?
- Yes
Replace A/C cycling switch. Do not discharge system. A/C cycling switch has a Schrader valve. Restore vehicle. Retest system.
- No
Discharge system and service. Retest system.
D19 CHECK A/C SWITCH OUTPUT
- Turn ignition switch to RUN.
- Turn A/C damper door switch to the OFF position.
- Using a test lamp, check for voltage at Pin 4 Circuit 348 (P) at A/C, heater switch connector.
- Did test lamp illuminate?
- Yes
Replace A/C damper door switch. Restore vehicle. Retest system.
- No
Go to D20.
D20 CHECK FOR VOLTAGE TO A/C CLUTCH
- Using a test lamp, check Circuit 347 (BK/Y) for voltage.
- Did test lamp illuminate?
- Yes
Replace A/C compressor clutch control relay. Restore vehicle. Retest system.
- No
Condition does not exist at this time. Retest system.