Vacuum Leak Diagnosis

A1 CHECK CONNECTORS

- Check in-line and control assembly multiple connectors for proper connection.

- Does hiss stop?

- Yes
Recheck system for proper operation.

- No
Go to A2.

A2 DETERMINE LEAKING VALVE

- Move function lever to determine what selector valve positions are leaking.

- Do all positions leak?

- Yes
Go to A3.

- No
Go to A5.

A3 CHECK SOURCE TUBE

- Check vacuum source tube (black) from A/C vacuum reservoir tank and bracket to control assembly for cut or disconnection

- Does hiss stop?

- Yes
Service tube. Recheck system for proper operation.

- No
Go to A4.

A4 PINCH OFF SOURCE TUBE

- Pinch off source tube (black) at control assembly.

- Does hiss stop?

- Yes
Replace selector valve. Recheck system for proper operation.

- No
Recheck source tube (black), connections, A/C vacuum reservoir tank and bracket and A/C vacuum check valve. Service or replace as required.

A5 DETERMINE LEAKING TUBE(S)

- Determine what color tube(s) are used in leaking function selector valve position(s).

- Pinch off suspect tube(s), one at a time, near each respective vacuum control motor.

- Does hiss stop?

- Yes
Check tube connection to vacuum control motor and service and/or reconnect if loose or split. Recheck for hiss. If hiss still continues, Replace vacuum control motor. Recheck system for proper operation.

CAUTION: Never manually operate any vacuum control motor or vacuum control motor controlled door--this may cause internal damage to the vacuum control motor diaphragm.

- No
Go to A6.

A6 PINCH OFF SUSPECT TUBE(S)

- Pinch off suspect tube(s), one at a time, near control assembly and/or in-line connector.

- Does hiss stop?

- Yes
Check tube for cut or damage. Service as required. Recheck system for proper operation.

- No
Replace function vacuum selector valve.