SERVICE A/C-FALSE CODE F46-F47 REPLACE BCM PROM

VEHICLES AFFECTED: 1988-89 C

Some 1988-1989 DeVilles and Fleetwoods that have sufficient air conditioning performance may experience a "Service Air Conditioning" telltale light with a false code F46 and/or F47 (A/C refrigerant system condition) that sets in ambient temperatures of 13 degrees - 18 degrees C (55-65 degrees F) The F46 and/or F47 code(s) are designed to set when a "low refrigerant" condition exists to protect the compressor.

This condition may be caused by a BCM PROM with an I.D. of:

I.D. Model Year ---- ---------- 22 or 23 1988 DeVille/Fleetwood 30 1989 DeVille/Fleetwood

The BCM PROM I.D. can be checked by entering diagnostics and selecting BCM parameter P.3.1 as described in Section 8D of the appropriate Cadillac Service Information Manual.

To repair this condition, replace the BCM PROM with the appropriate part number listed below:

Model Service Broadcast PROM Year Part Number Code I.D. ---- ----------- ---- ---- 1988 (all except commercial chassis) 16122026 ANAU 24 1988 (commercial chassis) 16122030 ANAW 224 1989 16138772 ARZT 31

IMPORTANT: The above PROM's also contain a purge feature that directs air flow to floor ducts at a high fan speed for 4.5 seconds when ignition is first turned on and A/C is required.

If replacing the BCM PROM does not repair this condition, perform a leak check on the refrigerant system. When checking for refrigerant leak's, the use of an electronic leak detector, J-29547 or equivalent, is recommended. When using the leak detector, check the bottom of the fittings at all connections because refrigerant is heavier than air.

Two system areas that should be checked thoroughly are the hose assembly at the compressor (any signs of oil leakage) and that all Schrader valve caps are tight because the cap O-ring is the primary seal.

If no leaks are found, discharge the refrigerant system as described in the appropriate Cadillac Service Information Manual, then check the orifice tube for debris and proper installation. The flow indication arrow on the orifice tube should point toward the evaporator.

Recharge system and check for leaks using an electronic leak detector.

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.