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Home › Dodge and Ram › 2000 › Ram Van B2500, Van Cargo Extended, 5.2 T › Repair and Diagnosis › Engine Performance › System › Engine Control Self-Diagnostics › Diagnostic Tests › Test NTC-15: Checking A/C System

Test NTC-15: Checking A/C System

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article.
  1. Turn ignition on with engine off. Using scan tool, check for DTCs. If DTC P0645: A/C CLUTCH RELAY CIRCUIT does not exist, go to next step. If DTC P0645: A/C CLUTCH RELAY CIRCUIT exists, perform DTC P0645: A/C CLUTCH RELAY CIRCUIT  test.
  2. Ensure A/C system is properly charged. If A/C system is properly charged, go to next step. If A/C system is not properly charged, recharge A/C system as necessary. Perform TEST VER-2 .
  3. Turn ignition on with engine off. Using scan tool, monitor A/C SELECT state. Turn A/C switch to ON and OFF positions several times while noting A/C SELECT state. If A/C SELECT state changes, go to next step. If A/C SELECT state does not change, repair open on A/C select circuit. A/C select circuit is the Light Green/Gray wire that goes from terminal C23 on Powertrain Control Module (PCM) connector C3 to terminal "A" on A/C heater control assembly. PCM is located on firewall, near brake booster. Perform TEST VER-2 .
  4. Check operation of clutch cycling switch. See appropriate article in AIR CONDITIONING & HEATING. Clutch cycling switch may also be referred to as A/C cycling switch. If clutch cycling switch operates properly, go to next step. If cycling switch does not operate properly, replace cycling switch. Perform TEST VER-2 .
  5. Turn ignition on with engine off. Turn A/C switch to ON position and place A/C fan switch in HIGH position while using scan tool to monitor A/C REQUEST state. If A/C REQUEST state changes, go to next step. If A/C REQUEST state does not change, go to step  12.
  6. Turn ignition off. Check operation of high pressure cut-off switch. See appropriate article in AIR CONDITIONING & HEATING. High pressure cut-off switch may also be referred to as high pressure cut-out switch or A/C high pressure switch. If high pressure cut-off switch operates properly, go to next step. If high pressure cut-off switch does not operate properly, replace high pressure cut-off switch. Perform TEST VER-2 .
  7. Check operation of low pressure cut-off switch. See appropriate article in AIR CONDITIONING & HEATING. Low pressure cut-off switch may also be referred to as low pressure cut-out switch or A/C low pressure switch. If low pressure cut-off switch operates properly, go to next step. If low pressure cut-off switch does not operate properly, replace low pressure cut-off switch. Perform TEST VER-2 .
  8. Ensure ignition is off. Disconnect A/C clutch connector at A/C compressor. Using ohmmeter, check resistance between ground and terminal No. 2 (Black wire) on A/C clutch connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on Black wire between A/C clutch connector and ground connection. Ground connection is located in engine compartment on the firewall, just directly below windshield wiper motor assembly. Perform TEST VER-2 .
  9. Ensure ignition is off and A/C clutch connector is still disconnected at A/C compressor. Remove A/C clutch relay from power distribution center. See Fig 1. Power distribution center is located at driver's side of engine compartment, near battery. Note cavities in power distribution center for A/C clutch relay. See Fig 1. Using ohmmeter, check resistance between cavity No. 5 (Dark Blue/Black wire) in power distribution center for A/C clutch relay and terminal No. 1 (Dark Blue/Black wire) on A/C clutch connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on Dark Blue/Black wire between A/C clutch connector and cavity No. 5 in power distribution center for A/C clutch relay. Perform TEST VER-2 .
  10. Ensure A/C clutch relay is still removed from power distribution center. Using voltmeter, check voltage at cavity No. 3 (Red/Yellow wire) in power distribution center for A/C clutch relay. See Fig 1. If voltage is more than 11 volts, go to next step. If voltage is 11 volts or less, repair open between battery, fuse No. 13 (20-amp) and Red/Yellow wire between fuse No. 13 and cavity No. 3 in power distribution center for A/C clutch relay. Fuse No. 13 is located in fuse block on end of driver's side of instrument panel, near door opening. Perform TEST VER-2 .
  11. Ensure ignition is off. Reinstall A/C clutch relay. Turn ignition on with engine off. Using scan tool, actuate A/C clutch relay. Using voltmeter, check voltage at terminal No. 1 (Dark Blue/Black wire) on A/C clutch connector. If voltage does not fluctuate between zero volts and 11 volts, replace A/C clutch relay. Perform TEST VER-2 . If voltage fluctuates between zero volts and 11 volts, replace electrical coil on A/C compressor for A/C clutch. Perform TEST VER-2 .
  12. Turn ignition off. Check operation of high pressure cut-off switch. See appropriate article in AIR CONDITIONING & HEATING. High pressure cut-off switch may also be referred to as high pressure cut-out switch or A/C high pressure switch. If high pressure cut-off switch operates properly, go to next step. If high pressure cut-off switch does not operate properly, replace high pressure cut-off switch. Perform TEST VER-2 .
  13. Check operation of low pressure cut-off switch. See appropriate article in AIR CONDITIONING & HEATING. Low pressure cut-off switch may also be referred to as low pressure cut-out switch or A/C low pressure switch. If low pressure cut-off switch operates properly, go to next step. If low pressure cut-off switch does not operate properly, replace low pressure cut-off switch. Perform TEST VER-2 .
  14. It is assumed that an open exists on A/C request circuit. A/C request circuit is the Dark Blue wire that goes from terminal C22 on PCM connector C3 to terminal No. 2 on high pressure cut-off switch and then from high pressure cut-off switch to clutch cycling switch, then to low pressure cut-off switch and to terminal No. 2 on A/C heater control assembly. A/C request circuit may also be referred to as A/C pressure signal. Repair open on A/C request circuit. Perform TEST VER-2 .
    Fig 1: Locating Fuses, Relays & Identifying Cavities In Power Distribution Center
    G00015549Courtesy of DAIMLERCHRYSLER CORPORATION
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