A/C PROGRAM NOT SETTING CODES (ECC) LOW REFRIGERANT LEVELS

SUBJECT: ELECTRONIC CLIMATE CONTROL DIAGNOSIS

MODELS AFFECTED: 1992 ELDORADOS AND SEVILLES (PRIOR TO VIN BREAKPOINTS NU607468 AND NU810265)

Some 1992 Eldorados (prior to VIN breakpoint NU607468) and Sevilles (prior to VIN breakpoint NU810265) were built with Air Conditioning Programmers (ACP's) which will not set codes for very low A/C refrigerant and which do not properly indicate A/C low refrigerant pressure switch status in on-board diagnostics.

- The low refrigerant status light (rear defrost symbol) is always on while in diagnostics, regardless of actual switch position and ACP input AI01 will always remain on "HI".

- ACP codes AD47 and AD48 will not set to indicate very low freon conditions.

Before diagnosing climate control system conditions on vehicles prior to the breakpoint, check the ACP software I.D., parameter AD99. If AD99 is 8640, replace the programmer with GMSPO P/N 16176559.

After replacing the programmer, proceed to diagnose the customer condition or symptoms by starting with tire "ECC System Check" char in Section 1C of the 1992 Service Information Manual.

Parts are currently available from GMSPO.

For warranty purposes use Labor Operation D0770 at .5 hour.

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.