Service Manual

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(5) Temperatures and thermistor resistance table
(6) Motor resistance table
Cautions:
• Before disconnecting the motor connectors, make sure that the power is turned OFF and the circuit
board is discharged adequately.
• Even after the power supply is cut off, the capacitor is charged. Therefore, high voltage is applied to
the motor for a while. Make sure that the LEDs on the circuit boards are turned OFF before starting
work.
• Never touch the circuit board while the power is ON. It causes electric shock and failure of the unit.
Replace the fan motor in the following cases.
[1] If it is hard to rotate the motor shaft by hand
[2] If the resistance between the motor leads is significantly different from the values specified in the table below
*Before measuring the resistance, the motor connectors must be disconnected from the circuit board.
<LGH-F300RVX2-E, LGH-F380RVX2-E>
Pin No.
Supply fan motor 3-1 3-4 3-5 3-6
Exhaust fan motor 4-1 4-5 4-6 4-7
Normal resistance About 815 kΩ About 40 kΩ About 105 kΩ ∞ kΩ
<LGH-F470RVX2-E, LGH-F600RVX2-E, LGH-F940RVX2-E, LGH-F1200RVX2-E>
Pin No.
Supply fan motor 3-1 3-4 3-5 3-6
Exhaust fan motor 4-1 4-5 4-6 4-7
Normal resistance ∞ kΩ About 50 kΩ About 150 kΩ ∞ kΩ
Temperature
Resistance
value (kΩ)
Temperature
Resistance
value (kΩ)
Temperature
Resistance
value (kΩ)
Temperature
Resistance
value (kΩ)
Temperature
Resistance
value (kΩ)
(°F) (°C) (°F) (°C) (°F) (°C) (°F) (°C) (°F) (°C)
-22 -30 64.2 to ∞ 19.4 -7 19.4 46.4 8 9.9 73.4 23 5.4
100.4 38 3.1
… … …
21.2 -6 18.5 48.2 9 9.5 75.2 24 5.2 102.2 39 3.0
-4.0 -20 37.2 23.0 -5 17.7 50.0 10 9.1 77.0 25 5.0
104.0 40 2.9
-2.2 -19 35.3 24.8 -4 16.9 51.8 11 8.7 78.8 26 4.8
105.8 41 2.8
-0.4 -18 33.5 26.6 -3 16.1 53.6 12 8.4 80.6 27 4.6
107.6 42 2.7
1.4 -17 31.8 28.4 -2 15.4 55.4 13 8.0 82.4 28 4.5
109.4 43 2.6
3.2 -16 30.2 30.2 -1 14.7 57.2 14 7.7 84.2 29 4.3 111.2 44 2.5
5.0 -15 28.7 32.0 0 14.0 59.0 15 7.4 86.0 30 4.2 113.0 45 2.5
6.8 -14 27.3 33.8 1 13.4 60.8 16 7.1 87.8 31 4.0 114.8 46 2.4
8.6 -13 26.0 35.6 2 12.8 62.6 17 6.8 89.6 32 3.9 116.6 47 2.3
10.4 -12 24.7 37.4 3 12.3 64.4 18 6.6 91.4 33 3.7 118.4 48 2.2
12.2 -11 23.6 39.2 4 11.8 66.2 19 6.3 93.2 34 3.6
120.2 49 2.2
14.0 -10 22.4 41.0 5 11.3 68.0 20 6.1 95.0 35 3.5
122.0 50 2.1
15.8 -9 21.4 42.8 6 10.8 69.8 21 5.8 96.8 36 3.3
… … …
17.6 -8 20.4 44.6 7 10.3 71.6 22 5.6 98.6 37 3.2 194 90 0 to 0.7
* Measure the return air (RA) thermistor resistance across pin No. 1 and 2 of CN5, and the outdoor air (OA)
thermistor resistance across pin No. 1 and 3 of CN7.
Supply fan motor connector
Exhaust fan motor connector