COIL RESISTANCE TEST
- Disconnect and isolate the negative battery cable.
- Disconnect the wire harness connector from the A/C clutch coil connector.
- Use an ohm meter and Back Probe Tool (special tool #6801, Terminal Probe) and measure the resistance of the A/C clutch coil at the coil connector terminals.
- See «A/C CLUTCH COIL SPECIFICATIONS»(ref-485594-S04495399822012071300000) chart for the acceptable A/C clutch coil resistance. Specifications apply for a work area temperature of 21° C (70° F). If the A/C clutch coil reading is below specifications, the coil is shorted and must be replaced. If the A/C clutch coil reading is above specifications, the coil is open and must be replaced.
COIL CURRENT DRAW TEST
- Verify the battery state of charge. Refer to «BATTERY, DIAGNOSIS AND TESTING»(ref-485500-S20209363092012071300000) .
- Connect an ammeter (0 to 10 ampere scale selected) in series with the A/C clutch coil feed terminal using Back Probe Tool (special tool #6801, Terminal Probe). Connect a voltmeter (0 to 20 volt scale selected) to measure voltage across the battery and the clutch coil.
- With the heater-A/C control in the A/C mode and the blower 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 coil supply voltage should be within two volts of the battery voltage. If the coil supply voltage is OK, go to 5 . If the coil supply voltage is not within two volts of battery voltage, test the clutch coil feed circuit for excessive voltage drop and repair as necessary.
- See «A/C CLUTCH COIL SPECIFICATIONS»(ref-485594-S04495399822012071300000) chart for the acceptable A/C clutch 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 coil current reading is zero, the coil is open and must be replaced. If the A/C clutch coil current reading is above specifications, the coil is shorted and must be replaced.
| Coil Resistance | Current Draw |
|---|---|
| 3.6 ± 0.2 ohms | 3.2 - 3.3 amps @ 11.5 - 12.5 volts |
A/C CLUTCH COIL SPECIFICATIONS