SPX Cooling Technologies 92-1322C - Manual (Page 13)

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2. If the contactor does not operate, check voltage across terminal N
on the circuit board and NO on the relay mounted on the circuit board
—21-29 volt required. If voltage is present across the coil—N to NO—
the contactor coil is defective and the contactor must be replaced. If
voltage is not present, the circuit board relay is defective and the circuit
board must be replaced.
C. If the green LED is off and the red LED is also off the problem is either
the circuit board, the sensor probe, or the transformer. To determine
which check as follows:
1. Disconnect power and remove wires T1 and T2 from the circuit
board. Replace with the 1.5K ohm resistor provided. See Figure 2.
If the system now works, the sensor probe is defective and must be
replaced. If the system does not work, go to step 2.
2. Reconnect power and take a voltage reading across N and 24/240
on the circuit board—21-29 volts required. If proper voltage is not
present the transformer is defective and must be replaced. If proper
voltage is present go to step 3.
3. Take a voltage reading across N and NO—21-29 volts required. If
proper voltage is not present, replace circuit board.
6. The sensor assembly can be checked for accuracy in the following
manner.
Remove wires T1 and T2 from the circuit board and measure ohm
readings across these wires. Measure the water temperature that the
probe is being exposed to. Compare with the following values.
Temp °F ohms
0 4273
10 3126
20 2312
32 1633
40 1305
45 1138
60 765
75 525
85 412
/ Troubleshooting /
Table 4