HUSSMANN CORPORATION • BRIDGETON, MO 63044-2483 • Printed in USA
Revised August 1, 1996 P/N 340272A
4 - 9
Troubleshooting—Compressor Board (Mechanical Low Pressure Control or Series Switchback)
Be sure Board Switch is closed.
Run, Refrigeration Mode
Voltmeter Voltmeter Action
Lead Placement Readings
Lead 1 Lead 2
1 T7 T8 120 Go to 2
0 Check Power Supply to Board
2 T5 T8 120 Go to 3
0 Check Power Supply to T5 from X1A
3 T6 T8 120 Go to 4
0 Alarm Circuit open – correct cause and reset
4 T4 T8 120 Go to 5
0 Failed connection between T7 and T4 – Repair
5 P1,1 T8 120 Go to 7
0 Test “ON/OFF” Switch and connections to Board –
If OK, Board Failure
6 P1,2 T8 120 Low Pressure Control closed – Go to 7
0 Low Pressure Control opened – Should be closed to
continue Board check
7 P1,3 T8 120 Go to 8
0 Board Failure
8 P1,8 T8 120 Go to 9
0 Compressor Protector open,
9 P2,2 T8 120 Go to 10
0 Board Failure
10 P1,5 T8 120 Go to 11
0 Check Fuse and connections – If OK, Board Failure
11 P1,6 T8 120 Go to 14
0 Alarm tripped - Go to 12
12 P1,4 T8 0 Go to 13
120 High Pressure Alarm – Correct cause and reset
13 P1,7 T8 0 Go to 14
120 Oil Alarm – Correct cause and reset
14 P2,3 T8 120 Go to 15
0 If K1 Contacts are open, correct and reset
If closed, Board Failure
15 P2,5 T8 0 Circuit Complete – End Test
120 Board Failure
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