For 1990-2009 cars

# LOW HEATER OUTPUT INSTALL NEW THERMOSTAT

#### VEHICLES AFFECTED: 1985 Oldsmobile 98 Equipped with Electronic Temperature Control (C65)

To repair low heater output on 1985 Ninety-Eight C65 equipped cars, two things can be done:

1. A 195 deg. thermostat should be installed, making sure that all air in purged from the cooling system using the published procedures.

2. The Programmer should then be reset by turning the calibration potentiometer 1/4 turn clockwise. This will accomplish two important things.

a. The initial warmup will be quicker in -18 deg. to 0 deg.C (0 deg. to 30 deg.F) ambient temperatures.

b. The heat distribution to the interior of the car will be much improved.

The potentiometer can be accessed through the back of the glove box as follows:

1. Locate and mark a position on the back of the glove box 4-7/8 in. from the right side and 1-1/8 in. up from the bottom of the box. See Figure 2.

2. Using a 3/8 in. drill bit with a depth stop or a piece of hose slipped over it to limit penetration to 1/4 in., drill a hole at the above marked location.

3. Fabricate, from a piece of 1/8 in. welding rod using the dimensions shown in Figure 2, a tool to turn the potentiometer 1/4 turn clockwise. The potentiometer can be accessed through the hole drilled in Step 2. See Figure 3.

Use the most applicable labour operation from the Canadian Labour time Guide and claim 0.3 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.