1993 Geo Storm Base, AutomaticFACTORY OEM SERVICE PROCEDURE

A/C Clutch System Functional Check

  1. With engine running, turn A/C on and off while noting A/C clutch operation. If A/C clutch does not engage, go to next step. If A/C clutch engages, A/C clutch control system is okay.
  2. Install scan tester and request A/C. Scan tester should display YES for A/C request and ON for A/C clutch. If scan tester does not display correctly, go to next step. If scan tester displays correctly, problem exists in A/C clutch power or ground circuit.
  3. With engine off and ignition on, connect test light to ground and probe Green/Orange wire at ECM connector with A/C requested. ECM is located on left side of instrument panel and contains 24-pin and 32-pin connectors.
  4. If test light glows, go to step 7). If test light does not glow, turn ignition off. Remove A/C thermo relay, located in relay box at right corner of engine compartment, near strut tower.
  5. Turn ignition on with A/C requested. Connect test light to ground. Probe Green/White wire of A/C thermo relay. If test light glows, go to next step. If test light does not glow, check for open pressure switch or open circuit in Green/White wire from A/C thermo relay to pressure switch. Pressure switch is located near receiver-drier.
  6. Check for open circuit in Pink/Green wire between A/C thermo relay and thermoswitch. Thermoswitch is located behind right side of instrument panel, near blower motor, and contains Purple/Green, Green/Yellow and Pink/Green wires. Check for open circuit in Green/Orange wire from A/C thermo relay to ECM. Check for defective thermoswitch or A/C thermo relay.
    NOTE: On Storm GSi A/T, also check for defective A/C control unit by disconnecting electrical connector at A/C control unit and installing jumper wire between Green/Orange and Gray/Red wires. A/C control unit is located behind right side of instrument panel, near blower motor.
  7. Connect test light to battery voltage. Backprobe Gray/Red wire at ECM. ECM is located on left side of instrument panel and contains 24-pin and 32-pin connectors. If test light glows, go to next step. If test light does not glow, check for defective ECM connector or ECM.
  8. Check for open circuit in Green wire between compressor relay and cut-out switch on A/C compressor. Compressor relay is located in relay box at right corner of engine compartment, near strut tower.
  9. Check for defective compressor relay or cut-out switch or defective connections. Check for open circuit in Gray/Red wire between ECM and diode assembly, located in relay box at right corner of engine compartment, near strut tower.
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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.

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