A/C - Air Flow Doesn't Shift From Defrost to Blend/Defog
Group Ref.: HVACBulletin No.: 331107
Date: December, 1993
SUBJECT:
AIR FLOW DIRECTION DOES NOT SHIFT FROM DEFROST MODE TO BLEND/DEFOG MODE (REINSTALL/REPLACE SPRING)
MODELS:
1994 BUICK ROADMASTER
1994 CADILLAC FLEETWOOD
1994 CHEVROLET CAPRICE
CONDITION:
Some owners may comment they do not perceive a shift in airflow direction after switching from defrost mode to blend/defog mode. (Chevrolet refers to this mode as "blend". Buick and Cadillac refer to this mode as "defog".) The airflow would continue to exit from the defrost outlet after changing modes. Airflow in blend/defog mode should be approximately 45 percent from the defrost outlet and 45 percent from the heater outlet with the rest exiting the side window defog outlets. Air flow in defrost should be primarily from the defrost outlet.
CAUSE:
The heater/defrost valve return spring is missing or dislodged.
CORRECTION:
1. Using high blower motor speed, verify airflow after shifting from defrost to blend/defog. (This condition will not be present after shifting from heater mode to blend/defrost.)
2. Locate the heater/defroster valve and verify that the spring is present and/or in the correct position. (See Figure 1).
3. If the spring is present, but not attached to the heater/defroster valve, reinstall per Figure 1. If it is not present, replace with P/N 3094308.
PART AVAILABILITY:
Parts are currently available from GMSPO.
WARRANTY INFORMATION:
For vehicles repaired under warranty, use:
Labor Operation: T-3418
Labor Operation Time: 0.2 Hr.