A: VENT DOES NOT OPERATE
Pinpoint Test A: Vent Does Not OperateA1 CHECK SYSTEM AIRFLOW
- With engine running and heater blower motor switch on high, check system airflow in each A/C damper door switch position to determine which position(s) have incorrect air flow. Refer to vacuum application chart for correct system air flow.
- Is airflow from the Defroster outlets for all positions?
- Yes
Go To A2.
- No
Go To A13.
A2 CHECK VACUUM SUPPLY HOSE
- Check vacuum supply hose to be sure it is connected to both the engine manifold and vacuum check valve.
- Is hose disconnected?
- Yes
Reconnect hose. Go to A1.
- No
Go to A3.
A3 LEAK CHECK VACUUM SUPPLY HOSE
- Disconnect vacuum supply hose from engine manifold fitting and from check valve. Plug one end of hose and leak test with vacuum pump.
- Does hose leak?
- Yes
Repair or replace vacuum hose. Go to A1.
- No
Connect hose to manifold fitting. Go to A4.
A4 CHECK VACUUM CHECK VALVE
- Check vacuum check valve for correct installation by removing the reservoir hose and the control assembly source hose (one at a time) from check valve and check for vacuum. Engine must be running for this test.
- Is vacuum available at both check valve ports?
- Yes
Reconnect both hoses. Go to A6.
- No
Go to A5.
A5 INSPECT VACUUM CHECK VALVE
- Inspect vacuum check valve for an obstruction and/or proper operation. Air flow through the check valve should be in the direction toward engine (Engine connection side is marked VAC).
- Is check valve plugged or obstructed?
- Yes
Replace check valve. Go to A1.
- No
Go to A6.
A6 LEAK TEST VACUUM CHECK VALVE
- Remove vacuum check valve from vehicle. Connect two hoses and a Tee fitting to outlet ports of check valve. Connect vacuum tester to Tee fitting.
- Pump 15 inches vacuum on check valve and observe gauge reading. If vacuum loss exceeds 1 inch per minute, remove check valve from tester and plug vacuum hoses. Pull a vacuum with the tester to be certain hoses and tester are not cause of leak.
- If tester and hoses do not leak, check valve for cause of leak.
- Does check valve lose more than 1 inch vacuum in one minute?
- Yes
Replace check valve. Go to A1.
- No
Reinstall check valve and Go to A7.
A7 CHECK VACUUM RESERVOIR
- Connect Vacuum Tester to vacuum reservoir and leak test reservoir. Reservoir must hold vacuum.
- Does reservoir leak?
- Yes
Replace reservoir. GO to A1.
- No
Connect hose to reservoir. Go to A8.
A8 CHECK SUPPLY HOSE
- Disconnect and plug BLACK supply hose at A/C control. Disconnect other end of supply hose from check valve and leak test hose with vacuum tester.
- Does supply hose leak?
- Yes
Service or Replace hose. Go to A1.
- No
Remove plug and Reconnect vacuum hoses. Go to A9.
A9 CHECK CONTROL ASSEMBLY
- Disconnect vacuum harness at in-line multiple connector near control. Plug all vacuum hoses except BLACK. Connect vacuum tester to BLACK hose. Select each function position, apply 15 inches vacuum and check for vacuum drop. Drop should not exceed 1 inch vacuum per minute for any function position.
- Does drop exceed 1 inch vacuum per minute?
- Yes
Note function positions where vacuum drops. Go to A1.
- No
Go to A11.
A10 LEAK TEST CONTROL ASSEMBLY
- Remove vacuum harness from A/C control. Connect vacuum tester to control supply port and plug control port that indicated a leak in step A9. Select function positions noted in Step A9 and apply 15 inches vacuum after selecting each position. Vacuum drop should not exceed 1/2 inch per minute.
- Does vacuum drop exceed 1/2 inch in one minute?
- Yes
Replace A/C control. Go to A1.
- No
Go to A12.
A11 CHECK SUPPLY HOSE
- Disconnect BLACK supply hose from check valve. Connect vacuum tester to supply hose and operate tester as if pulling a vacuum. If tester can pull a vacuum, hose is plugged. If tester pulls a partial vacuum, hose is restricted.
- Is hose plugged or restricted?
- Yes
Replace supply hose. GO to A1.
- No
Go to A15.
A12 LEAK TEST JUMPER VACUUM HARNESS
- Plug one end of vacuum hose that indicated a leak in step A9. Apply 15 inches vacuum to hose and observe vacuum gauge. Vacuum should not drop.
- Does vacuum drop?
- Yes
Repair or replace vacuum jumper harness. Go to A1
- No
Check connection of vacuum harness to A/C control for leak. Repair or replace vacuum jumper harness. Go to A1.
A13 EVALUATE SYSTEM AIR FLOW
- Is the air flow in step A1 correct for each function position?
- Yes
Go to A14.
- No
Go to A15.
A14 ISOLATE LEAKING VACUUM CIRCUIT
- Repeat step A1 and accelerate engine speed for each function position.
- Does air flow go to defrost during acceleration?
- Yes
Go to A19.
- No
Go to A15.
A15 REVIEW VEHICLE HISTORY
- Did system function properly prior to this complaint?
- Yes
Go to A18.
- No
Go to A16.
A16 CHECK VACUUM HOSES
- Check each vacuum hose to be sure it is not plugged.
- Is a hose plugged?
- Yes
Replace vacuum hose. Go to A1.
- No
Go to A17.
A17 CHECK VACUUM HARNESS
- Compare vacuum hose colors in each vacuum harness to the vacuum schematic.
- Do the hose colors agree with the schematics?
- Yes
Go to A18.
- No
Replace vacuum harness. Go to A1.
A18 CHECK VACUUM CIRCUIT
- Check vacuum circuit for pinched or kinked vacuum hose
- Is hose pinched or kinked?
- Yes
Unkink or replace vacuum hose. Go to A1.
- No
Go to A19.
A19 CHECK VACUUM CIRCUIT CONNECTIONS
- Check each vacuum hose connection to determine if it is partially connected or disconnected.
- Is a vacuum hose connection disconnected or partially connected?
- Yes
Reconnect hose. Go to A1.
- No
Go to A20.
A20 CHECK VACUUM HOSE
- Disconnect both ends of vacuum hose in suspected circuit. Plug one end and leak test with vacuum tester.
- Does vacuum hose leak?
- Yes
Repair or replace hose. Go to A1.
- No
Go to 21
A21 CHECK VACUUM MOTOR
- Check vacuum motor for leaks with vacuum tester.
- Does motor hold vacuum?
- Yes
Go to A22.
- No
Replace vacuum control motor. Go to A1.
A22 CHECK VACUUM MOTOR INSTALLATION
- Check attachment of vacuum motor arm to damper door.
- Is motor arm attached to door or door crank arm?
- Yes
Check for binding or damaged damper door. Repair or replace damper door. Go to A1.
- No
Connect motor arm to door and/or crank arm and check operation. Go to A1.