INADEQUATE HEAT CONDITION HEATER CORE P/N MAY REPAIR

MODELS/YEARS ALL 1988 CUTLASS SUPREME MODELS WITH C40 OR C67

Some 1988 Cutlass Supreme models with C40 or C67, built prior to the VIN JD351794 may experience an inadequate heat condition due to a missing separator in the heater core. If a vehicle exhibits this condition, the following diagnostic procedure should be used:

1. Run the vehicle until the thermostat opens. The vehicle must be at normal operating temperature.

NOTE: This may be accomplished by (a) physically driving the vehicle to achieve operating temperature or (b) letting the vehicle idle in the service area and visually monotor the coolant flow or record the coolant temperature using a Tech I Scan tool. If method (b) is used, it may be necessary to block off the radiator to restrict air flow to aid in achieving operating temperature.

2. The remaining procedure must be conducted at 60 DEG - 80 DEG Fahrenheit ambient temperature in order to properly diagnose the heater core performance.

NOTE: Conducting this test at 60 DEG - 80 DEG Fahrenheit will ensure proper performance of the heater core in cooler ambience.

3. Set control to HEATER mode ("lower') and temp lever to full 'warm'.

4. Set fan speed on HIGH.

5. Engine speed at IDLE.

6. Check the vehicle heater outlet temperature for several minutes with a thermometer.

NOTE: The outlet temperature should be a minimum of 50 DEG Fahrenheit higher than the ambient temperature.

If outlet temperature is less than 50 DEG Fahrenheit above ambient, the heater core should be replaced with P/N 3091147.

Parts are currently available from GMSPO.

Labor Operation Number: T7765 Check heater performance (includes measuring air temperature at heater outlet). Labor Time: .3 Hours

If necessary to replace heater core; use applicable labor operation and time.

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.