10. CHECKING ELECTRICAL COMPONENTS
10-1. Measurement of Insulation Resistance
The insulation is in good condition if the resistance exceeds 1M ohm.
10-1-1. Power Supply Cord
Clamp the grounding wire of power cord with the lead clip of the insulation resistance tester and measure the resistance by placing a probe on either of the two power wires. (Fig. 1)
Then also measure the resistance between the grounding and other power terminals. (Fig. 1)
Ground wire
Clip
Probe
Insulation tester
Fig. 1
Terminal plate
Probe
10-1-2. Indoor Unit
Clamp an aluminum plate fin or copper tube with the lead clip of the insulation resistance tester and measure the resistance by placing a probe on each terminal screw on the terminal plate. (Fig. 2)
Note that the ground line terminal should be skipped for the check.
10-1-3. Outdoor Unit
Clamp a metallic part of the unit with the lead clip of the insulation resistance tester and measure the resistance by placing a probe on each terminal screw where power supply lines are connected on the terminal plate. (Fig. 2)
10-1-4. Measurement of Insulation Resistance for Electrical Parts
Disconnect the lead wires of the desired electric part from terminal plate, capacitor, etc. Similarly disconnect the connector. Then measure the insulation resistance. (Figs. 3 and 4)
NOTE
Refer to Electric Wiring Diagram.
If the probe cannot enter the poles because the hole is too narrow then use a probe with a thinner pin.
Clip
Copper tube or metallic part
Clip
Copper tube or metallic part
Metallic part 
Clip
Insulation tester
Fig. 2
Probe
Insulation tester
Fig. 3
From fan motor, compressor and other parts
Probe
Insulation
Fig. 4 tester
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