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Vacuum System Test

WARNING: This page is about a different car, the 1997 Oldsmobile Cutlass Supreme. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Go to TROUBLE SHOOTING and perform OUTLET AIRFLOW INCORRECT  before proceeding with the following test.
  1. Start engine and let idle. Check vacuum supply (Black vacuum hose) to vacuum/electric solenoid assembly. Vacuum should be about 18 in. Hg and remain at 18 in. Hg when engine is turned off.
  2. Check each vacuum actuator by disconnecting vacuum hose and applying vacuum directly to actuator. Repair or replace actuator as necessary. See Fig 1.
  3. Reconnect all vacuum and electrical connections. Run engine and cycle through all modes on A/C-heater control panel while observing vacuum actuators. Check for vacuum to actuators by observing vacuum actuator position. When vacuum is applied, actuator will retract.
  4. If an actuator retracts when it should not, replace A/C-heater control panel. If an actuator does not retract, check for vacuum leaks, collapsed vacuum hoses or binding valves. If components are okay, replace vacuum/electric solenoid assembly.
Fig 1: Air Delivery/Vacuum Distribution Chart
G96J31103Courtesy of GENERAL MOTORS CORP.
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