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Improper Air Delivery

WARNING: This page is about a different car, the 1996 Buick Roadmaster. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition switch to RUN position. Turn A/C-heater control panel to AUTO at 75°F (24°C). Using a test light connected to ground, backprobe terminal No. 6 (Brown wire) of vacuum/electric solenoid. See Fig 1. If test light glows, go to next step. If test light does not glow, repair open or short to ground in Brown wire.
  2. Turn ignition off. Disconnect vacuum/electric solenoid connector. Using ohmmeter, measure resistance between vacuum/electric solenoid terminal No. 6 (Brown wire) and vacuum/electric solenoid terminals No. 1 (Light Green wire), 2 (Red wire), 3 (Purple wire), 4 (Tan wire), and 5 (Light Blue wire). If resistance is 70-120 ohms for all terminals, go to next step. If resistance is not 70-120 ohms for all terminals, check vacuum/electric solenoid connections. If connections are okay, replace vacuum/electric solenoid.
  3. Connect vacuum/electric solenoid connector. Turn ignition switch to RUN position. Turn A/C-heater control panel to OFF position. Using a test light connected to battery voltage, backprobe vacuum/electric solenoid terminals No. 1 (Light Green wire), No. 2 (Red wire), No. 3 (Purple wire), No. 4 (Tan wire) and No. 5 (Light Blue wire). If test light glows at terminal No. 4, and does not glow at all other terminals, go to step 5). If test light does not glow as specified, go to next step.
  4. Check for open or short to battery voltage in Tan wire. Check for short to ground in Light Green wire, Red wire, Purple wire and Light Blue wire circuits. Check connections at A/C-heater control panel connections. If wiring and connections are okay, replace A/C-heater control panel.
  5. Check for short to ground in Tan wire and repair as necessary. If Tan wire is okay, turn A/C-heater control panel to AUTO and temperature to 60°F (16°C). Using a test light connected to battery voltage, backprobe vacuum/electric solenoid connector terminals No. 1 (Light Green wire), No. 2 (Red wire), No. 3 (Purple wire), No. 4 (Tan wire) and No. 5 (Light Blue wire). If test light glows at terminals No. 2 and 3, and does not glow at terminals No. 1, 4 and 5, go to step 7). If test light does not glow as specified, go to next step.
  6. Check for open or short to battery voltage on Red wire and Purple wire circuits. Check for short to ground in Light Green wire, Tan wire and Light Blue wire circuits. Check A/C-heater control panel connections. If circuits and connections are okay, replace A/C-heater control panel.
  7. Check for short to ground in Red wire and Purple wire circuits. If circuits are okay, turn A/C-heater control panel to AUTO and set temperature to 90°F (32°C). Using a test light connected to battery voltage, backprobe vacuum/electric solenoid connector terminals No. 1 (Light Green wire), No. 2 (Red wire), No. 3 (Purple wire), No. 4 (Tan wire) and No. 5 (Light Blue wire). If test light glows at terminals No. 4 and 5, and does not glow at terminals No. 1, 2 and 3, go to next step. If test light does not glow as specified, check A/C-heater control panel connections. If connections are okay, replace A/C-heater control panel.
  8. Check for short to ground in Tan and Light Blue wire circuits. If circuits are okay, turn A/C-heater control panel to BLEND position. Using a test light connected to battery voltage, backprobe vacuum/electric solenoid connector terminals No. 1 (Light Green wire), No. 2 (Red wire), No. 3 (Purple wire), No. 4 (Tan wire) and No. 5 (Light Blue wire). If test light glows at terminal No. 5, and does not glow at terminals No. 1, 2, 3 and 4, go to next step. If test light does not glow as specified, check A/C-heater control panel connections. If connections are okay, replace A/C-heater control panel.
  9. Push A/C-heater control panel button for front defroster mode. Using a test light connected to battery voltage, backprobe vacuum/electric solenoid connector terminals No. 1 (Light Green wire), No. 2 (Red wire), No. 3 (Purple wire), No. 4 (Tan wire) and No. 5 (Light Blue wire). If test light glows at terminals No. 1 and 4, and does not glow at terminals No. 2, 3 and 5, go to next step. If test light does not glow as specified, check A/C-heater control panel connections. If connections are okay, replace A/C-heater control panel.
  10. Check for short to ground in Light Green wire and Tan wire circuits. If circuits are okay, push A/C-heater button for DEFOG mode. Using a test light connected to battery voltage, backprobe terminals No. 1 (Light Green wire), No. 2 (Red wire), No. 3 (Purple wire), No. 4 (Tan wire) and No. 5 (Light Blue wire). If test light glows at terminal No. 4, and does not glow at terminals No. 1, 2, 3 and 5, A/C-heater system is functioning properly. Perform VACUUM DIAGNOSIS. If test light does not glow as specified, check connections at A/C-heater control panel. If connections are okay, replace A/C-heater control panel.
Fig 1: Identifying Solenoid Module Harness Connector Terminals
G94F37312Courtesy of GENERAL MOTORS CORP.
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