Coil Current Draw Test
- Verify the battery state of charge. Refer to Electrical - Engine Systems/Battery System/BATTERY - Diagnosis and Testing .
- Connect an ammeter (0 to 10 ampere scale selected) in series with the clutch field coil feed terminal using Back Probe Tool 6801. Connect a voltmeter (0 to 20 volt scale selected) to measure voltage across the battery and the clutch coil.
- With the A/C-heater control in the A/C mode and the blower motor at low speed, start the engine and allow it to run at a normal idle speed.
- The A/C clutch should engage immediately, and the clutch field coil supply voltage should be within two volts of the battery voltage. If the field coil supply voltage is OK, go to 5. If the field coil supply voltage is not within two volts of battery voltage, test the clutch field coil feed circuit for excessive voltage drop and repair as necessary.
- See A/C CLUTCH COIL SPECIFICATIONS for the acceptable A/C clutch field coil current draw. Specifications apply for a work area temperature of 21° C (70° F). If voltage is more than 12.5 volts, add electrical loads by turning on electrical accessories until voltage reads below 12.5 volts.
- If the A/C clutch field coil current reading is zero, the coil is open and must be replaced.
- If the A/C clutch field coil current reading is above specifications, the coil is shorted and must be replaced.
A/C CLUTCH COIL SPECIFICATIONS
| Coil Resistance | Current Draw |
|---|---|
| 3.6 ± 0.2 ohms | 3.2 - 3.3 amps @ 11.5 - 12.5 volts |