96-04 Chev/GMC S/T Classic, 96-01 Oldsmobile S/T Classic: Heat Coming from Vents with HVAC Off- kw air hot leak temperature GMT325 GMT330

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Customer may comment that warm air blows out the heater ducts (floor vents) on a manual HVAC system, RPO-C60. The volume of air flow will be minimal and this condition can occur with the HVAC in any mode or in the off position.

This is a normal air bleed into the vehicle and no repair attempts should be made. The air bleeding into the vehicle may be warmer than ambient air because of the location of the heater core in the HVAC case.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

(1996-2004 Chevrolet Blazer 2WD and 4WD) and (1996-2004 Chevrolet S-10 Reg. Cab, Ext. Cab, Crew Cab 2WD and 4WD) and (1996-2004 GMC Sonoma Reg. Cab, Ext. Cab, Crew Cab 2WD and 4WD) and (1996-2004 GMC Jimmy 2WD and 4WD) and (1996-2001 GMC Envoy 2WD) and (4WD 1996-2001 Oldsmobile Bravada AWD)

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