TM 9-4110-258-13
2.2 FAULT CONTROLS AND INDICATORS.
The controls and indicators needed to monitor and reset a fault condition on the refrigeration unit are located on the
control box assembly and inside the condenser frame.
1
Thermometer (REFRIGERATOR TEMPERATURE). The thermometer will indicate more than 15F (7C)
above or below the remote bulb thermostat setting if a fault occurs in the temperature control system.
2
Pressure Gauge (DISCHARGE PRESSURE). The pressure gauge will indicate more than 250 psi (1725
kPa) or less than 165 psi (1138.5 kPa) if a fault occurs in the refrigeration system. At start up, shut down, or
operation in high temperatures, this range can go higher.
3 Compound Gauge (SUCTION PRESSURE). The compound gauge will indicate more than 15 psi (103.5
kPa)
or less than 0 psi (0 kPa) if a fault occurs in the refrigeration system. At shut down or operation in low
temperatures, this range can go lower.
4
Circuit Breaker (MAIN CIRCUIT BREAKER). The circuit breaker will be in a mid-way position if a fault has
caused excessive load on the electrical system. To reset the circuit breaker, move the handle to the OFF
position and then back to the ON position.
5
Reset Button (COMPRESSOR OVERLOAD). The reset button resets the motor starter if a fault has caused
the compressor to overload. Push the reset button to reset the motor starter.
6
Dual Pressure Control Switch. The dual pressure control switch will open the electrical control circuit if a
fault in the refrigeration system causes the pressure of the refrigerant gas leaving the compressor to exceed
300 psi (2070 kPa). The switch will automatically reset after a high pressure fault.
7
Differential Oil Pressure Switch. The differential oil pressure switch will open the electrical control circuit if a
fault in the refrigeration system causes the compressor oil pressure to drop. Push the reset button to reset
the differential oil pressure switch.
8
Sight Indicator (REFRIGERANT SIGHT GLASS). The sight indicator port will show continuous bubbles or
foam in the refrigerant if there is a fault in the refrigeration system. The center indicator color will be yellow if
moisture in the refrigerant exceeds safe operating limits.
9
Sight Glass (COMPRESSOR OIL SIGHT GLASS). The sight glass port will show the compressor oil level
less than up the port or will show the oil foaming if there is a fault in the refrigeration system.
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