WHITE POWDER COMING FROM A/C VENTS DURING OPER. (REPL EVAP)

Subject: WHITE POWDER COMING FROM A/C VENTS DURING OPERATION

Model and Year: 1993 CAPRICE

CONDITION:

--------- White dust or flakes can be emitted from the HVAC vents during operation.

CAUSE:

----- The dusting or flaking is caused by silicate coating flaking from the evaporator core. The flaking material is a non-crystalline silicone dioxide which represents no health or toxicity risk. This condition is initiated by usage of the A/C system including wetting and drying cycles of the evaporator core. The duration and amount of dust is variable and will disappear with time and usage. With regular A/C usage, some vehicles have stopped flaking within 2 or 3 days, although other vehicles may experience the condition for several weeks.

CORRECTION:

---------- Evaporator Core Replacement PART NUMBER 52458278 Replacement evaporator cores are not coated with silicate coating.

Even though this condition will disappear with use, some customers may request immediate correction. Service requires replacing the evaporator core. Although the evaporator core can be replaced per Service Information Manual procedures, the customer should be advised this is a complex operation including discharging and recharging the A/C refrigerant system. Since the condition will disappear, the options should be reviewed with the customer. If, in order to satisfy the customer the evaporator core needs to be replaced, please perform the procedure immediately.

Follow procedure in Service Manual, Section 1B1. For evaporator removal, it may be helpful to remove the evaporator studs. This can be accomplished by using a female E7 torx bit socket or by installing double nuts on studs.

NOTE: Water can leak onto carpeting during this procedure, it is recommended that a mat be placed on passenger side floor before removing lower evaporator case.

Module water core filter must be removed from evaporator core (by removing push pins) and transferred to new core. Before installing, thoroughly rinse filter with water and be certain that there is no remaining silicate material. Make sure filter is in the same orientation as original filter.

In addition to normal service procedure, the evaporator case and duct system should be thoroughly cleaned. Thoroughly vacuum or blow out inside of evaporator case, heater outlet and any accessible ducts. Wipe out upper and lower evaporator case interior with a damp cloth before installing evaporator.

After replacement of the evaporator core, the HVAC system should be cycled through all modes on high blower speed to dislodge any remaining particles. Thoroughly vacuum any surface of the vehicle where dust may have accumulated. Cleaning of the ducts and case is particularly critical in avoiding customer comebacks.

PART AVAILABILITY:

Parts are currently available from GMSPO.

WARRANTY INFORMATION:

Labor Operation: T3359

Labor Time: (RWD) 1.1 Hrs.

Add: to discharge and charge A/C system .7 Hrs.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.