Instrument Panel Vent - Leaking Air in Heater Modes
File In Section: 1 - HVACBulletin No.: 63-11-09
Date: January, 1997
Subject:
Air Coming From I/P Vent While In Heater Modes or a Delay Occurs When
Changing to a New Mode Setting (Diagnose/Modify/Replace)
Models:
1996-97 Buick Skylark
1996-97 Oldsmobile Achieva
1996-97 Pontiac Grand Am
Condition
Some owners may comment on one of the following conditions:
Condition A
Air is felt coming through the I/P vents while the HVAC system is in "Heater" modes. No air should be felt through the I/P vents in "Heater" modes.
Condition B
A delay occurs when changing to a new mode setting. The mode typically changes within 1 minute and is accompanied by a hissing sound.
Cause
Condition A
The mode door may not seal tightly to the HVAC module, allowing air to escape through the I/P vents.
Condition B
The mode switch/valve assembly may not immediately distribute vacuum to the appropriate HVAC module vacuum actuators.
Correction
Diagnose the system to determine the condition
Does air come out the I/P vents in ALL "Heater" modes (heat, blend, defrost) but responds correctly in all other modes? If "YES," go to diagnosis for Condition A (Mode Door Check). If "NO," go to Diagnosis for Condition B (Control Assembly Check).
Condition A
Diagnose
Mode Door Check
1. Remove I/P compartment. Refer to Section 8C2 in the Service Manual. Verify vacuum at the mode actuator (yellow label) red hose and observe door linkage movement. Make corrections if necessary and recheck. If condition was found, corrected, and air now comes out of the correct ducts based on the mode setting, reinstall the I/P compartment and STOP. If vacuum and door movement are verified and the air still comes out of the I/P vents in ALL "heater" modes, perform the service procedure listed below then STOP - DO NOT perform Diagnosis for Condition B.
Service Procedure
Modify mode door actuator linkage
1. Remove vacuum lines from mode door actuator.
2. Remove retaining clip at end of actuator shaft.
3. Remove actuator from HVAC module.
4. Drill 5/32 in. hole, 5 mm up the actuator link (closer to the actuator housing).
5. Install actuator to HVAC module.
6. Install mode door shaft to new hole on actuator link with retaining clip.
7. Install vacuum lines to actuator.
Verify that there is no air coming through the I/P vents in "Heater" modes with blower on "High." If leakage is still present through I/P vents, then diagnose HVAC module. Refer to Section 1B in applicable Service Manual.
Condition B
VIN Breakpoints
Diagnose
Control Assembly Check
While operating the HVAC system, a delay occurs when changing to a new mode setting. The mode change is typically accompanied by a hissing sound. This could occur in any one or more modes. It could be an intermittent event (possibly subject to ambient temperatures generally below 35° F (1° C). Therefore, the control assembly could operate correctly when it is checked.
1. Does air come out the correct ducts based on the mode setting? If "YES," perform the service procedure listed below. If "NO," go to Step 2.
2. Remove I/P compartment. Refer to Section 8C2 in the Service Manual. Verify vacuum at the source (purple hose) and at the vacuum actuators. Verify mode and defrost door operation. Make corrections if necessary. If condition was found, corrected, and air now comes out of the correct ducts based on the mode setting, reinstall the I/P compartment and STOP. If NOT, perform the service procedure listed below, then STOP. DO NOT perform the diagnosis for Condition A.
Service Procedure
Replace the mode switch/valve assembly.
1. Remove the control assembly from the vehicle. Refer to Section 1B of the applicable Service Manual.
2. Remove the mode switch/valve assembly from the control assembly (see Figure 1).
3. Install the mode switch/valve assembly to the control assembly, see part numbers listed below. Verify that the screws are fully seated and not stripped.
4. Install control assembly to vehicle.
5. Verify correct air distribution.
6. Complete installation.
Parts Information
P/N Description
1624B149 (For vehicles equipped without A/C,
RPO C41)
16248139 (For vehicles equipped with A/C,
RPO C60)
Parts are currently available from GMSPO.
Warranty Information
For vehicles repaired under warranty, use the table.