Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Blower Resistor Circuit Board
Remove blower resistor wiper arm assembly (see above and note CAUTIONS on loose ball bearings) . Take out three blower resistor circuit board retaining screws and two retaining screws in electrical connector body, then lift out blower resistor circuit board, electrical connector, and wiring as an assembly. Install this assembly by reversing removal procedure and adjust feedback potentiometer (see ADJUSTMENT in individual data for each car model) .
General Motors Automatic Temperature Control Testers are available and necessary to test and adjust ATC systems, Instructions for connecting and using the Testers are on cards attached to each Tester. The following table lists year car models and the correct Tester for each system.
| Model Year | Tester No. |
|---|---|
| 1969-70 | None |
| 1971-72 | J-23678 |
| 1969-70 | J-22368-01 or J-21512 | |
| 1971-72 (Front Unit) | J-23678 | |
| (Rear Unit) | J.-22368-01 or J-21512 | |
| 1969-70 | J-22368 |
| 1971-72 | J-23678 |
| 1969 (All Models) | J-22684-02 | |
| 1970 (Except Grand Prix) | J-22368 | |
| (Grand Prix) | J-22684-01 or J-22684-02 | |
| 1971-72 (Except Grand Prix) | J-23678 | |
| (Grand Prix) | J-22684-01 or J-22684-02 | |
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.