Coil Current Draw Test
- Verify the battery state of charge for any state of charge issues. Refer to BATTERY, DIAGNOSIS AND TESTING .
- 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 A/C 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 coil supply voltage should be within 2 volts of the battery voltage. If the clutch coil supply voltage is OK, go to Step 5 . If the coil supply voltage is not within 2 volts of battery voltage, test the clutch coil feed circuit for excessive voltage drop and repair as necessary.
- See A/C Clutch Coil Specifications table for acceptable A/C clutch coil current draw. Specifications apply for a work area temperature of 20°C (68°F). Refer to TECHNICAL SPECIFICATIONS . 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.