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Test 1A: Identifying A/C-Heater System Problems

WARNING: This page is about a different car, the 1999 Dodge Intrepid and 1999 Chrysler Concorde. However, it is still accessible from the selected car via links, so may be relevant.
  1. Connect scan tool to Data Link Connector (DLC). See Fig 1 . Using scan tool and the most current diagnostic program cartridge, ensure there is communication with Body Control Module (BCM) and Powertrain Control Module (PCM). If scan tool has a blank screen, go to next step. If any other communication problem exists, go to appropriate BODY CONTROL COMPUTER - VEHICLE COMMUNICATIONS article in ACCESSORIES & EQUIPMENT. If there are no communication problems, go to step  7 .
  2. Turn ignition off. Disconnect scan tool from DLC. Check connector for an open, loose or disconnected terminals. Repair as necessary.
  3. Using a DVOM, ensure there is continuity between ground and DLC terminals No. 4 (Black wire) and No. 5 (Black/Light Green wire). If continuity is present, go to next step. If continuity is not present, repair wire(s) as necessary.
  4. Using a DVOM, check voltage at DLC terminal No. 16 (Pink wire). If battery voltage is not present, go to next step. If battery voltage is present, go to step  6 .
  5. If battery voltage is not present, check fuse No. 19 (10-amp) located in junction block, behind end cover at left side of instrument panel. Replace fuse if blown. If fuse blows again, repair DLC battery feed circuit as necessary.
  6. Substitute scan tool cable with a known-good cable. If scan tool screen is no longer blank and scan tool is functioning properly, go to next step. If scan tool screen is still blank, replace defective scan tool. If there are no communication problems, go to next step.
  7. Using scan tool, select ENGINE, and then READ DTCS. If scan tool does not display any PCM DTCs, go to next step. See appropriate ENGINE PERFORMANCE - SELF-DIAGNOSTICS article if any of the following A/C-heater system related PCM DTCs are displayed:
    • ECT SENSOR VOLTAGE TOO LOW
    • ECT SENSOR VOLTAGE TOO HIGH
    • A/C PRESSURE SENSOR VOLTAGE TOO HIGH
    • A/C PRESSURE SENSOR VOLTAGE TOO LOW
    • LOW SPEED FAN CONTROL RELAY CIRCUIT
    • HIGH SPEED FAN CONTROL RELAY CIRCUIT
    • A/C CLUTCH RELAY CIRCUIT
    • ENGINE IS COLD TOO LONG
  8. Using scan tool, select BODY SYSTEM, BODY COMPUTER, SENSORS and then IGNITION VOLTAGE. Turn ignition on. If battery voltage is displayed, go to next step. If battery voltage is not displayed, go to appropriate BODY CONTROL COMPUTER article in ACCESSORIES & EQUIPMENT.
  9. Using scan tool, select BODY SYSTEM, BODY COMPUTER, and then READ DTCS. If A/C-heater system related BCM DTCs are not present, go to next step. If A/C-heater system related BCM DTCs are present, go to TEST 1B: IDENTIFYING A/C-HEATER DIAGNOSTIC TROUBLE CODES  .
  10. If no BCM DTCs exist and mode door is inoperative, go to TEST 19A: INOPERATIVE MODE DOOR in AUTOMATIC A/C-HEATER SYSTEMS - CONCORDE, INTREPID, LHS & 300M article. If no BCM DTCs exist and temperature control/blend air door is inoperative, go to TEST 15A: INOPERATIVE TEMPERATURE/BLEND AIR DOOR in AUTOMATIC A/C-HEATER SYSTEMS - CONCORDE, INTREPID, LHS & 300M article.
  11. If no BCM DTCs exist and mode door is inoperative, go to TEST 19A: INOPERATIVE MODE DOOR in AUTOMATIC A/C-HEATER SYSTEM - CONCORDE, INTREPID, LHS & 300M article. If no BCM DTCs exist and recirculation door is inoperative, go to TEST 12A: RECIRCULATION DOOR ACTUATOR TEST FAILURE in AUTOMATIC A/C-HEATER SYSTEMS - CONCORDE, INTREPID, LHS & 300M article.
  12. If rear window defogger is inoperative, see appropriate REAR WINDOW DEFOGGER article in ACCESSORIES & EQUIPMENT.
  13. If no BCM DTCs exist and blower motor is inoperative, go to TEST 8A: INOPERATIVE BLOWER MOTOR  . If no BCM DTCs exist and blower motor speed(s) are incorrect, go to TEST 9A: INCORRECT BLOWER MOTOR SPEEDS  . If no BCM DTCs exist and either A/C switch or rear defogger switch is inoperative, go to TEST 11A: INOPERATIVE CONTROL HEAD SWITCH  .
  14. If no BCM DTCs exist and there is a problem with A/C control head illumination, but instrument panel lights operate properly, go to TEST 10A: CONTROL HEAD ILLUMINATION  . If instrument panel lights do not operate properly, see appropriate ILLUMINATION/INTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT.
Fig 1: Locating Data Link Connector (DLC)
G98A04003Courtesy of CHRYSLER CORP.
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