INSUFFICIENT COOLING IN A/C MODE AND/OR CODE F48

SUBJECT: INSUFFICIENT COOLING IN A/C MODE AND/OR CODE F48 AND/OR PRESSURE RELIEF VALVE BLOW OFF

MODELS AFFECTED: 1991 DE VILLES AND FLEETWOODS

Some 1991 DeVilles and Fleetwoods with VIN breakpoints prior to M4217597 may experience insufficient cooling, code 48 for low pressure switch open, or pressure relief valve blow off due to dislocation of the orifice tube. To diagnose this condition:

A. Recover refrigerant from A/C system.

B. Separate tube assembly as shown in Figure 2, Item 3.

C. Inspect placement of orifice as shown in Figure 1.

If the orifice tube is properly located, refer to the Climate Control System Check in Section 1C of the Service Information Manual. If the orifice tube is not located properly, use the following procedure:

1. Remove evaporator tube (Figure 2, Items 2 and 6) assembly from evaporator inlet pipe and at condenser.

2. Remove complete assembly and replace with P/N 25550234 which includes the orifice tube.

NOTE: Coat 0-rings with clean 525 viscosity refrigerant oil and hand start fittings to prevent 0-ring damage and to secure a proper seal.

3. Torque to 24 N.m (18 lbs. ft.).

4. Be sure to fasten all A/C line clips to prevent grounding or distortion of tube. Refer to Figure 2, Views A, B, and C.

5. Evacuate, charge, and leak test A/C system.

Parts are currently available from GMSPO. For warranty purposes use Labor Operation T6526 at 1.4 hours.

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.