TM 9-4110-254-14
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 (REFRIGERATION TEMPERATURE). The thermometer will indicate more than 15F (70 C)
above or below the remote bulb thermostat setting if a fault occurs m the temperature control system.
2 Pressure Gage (DISCHARGE PRESSURE). The pressure gage will indicate more than 270 psi (1863 kPa) or
less than 160 psi (1104 kPa) if a fault occurs m the refrigeration system At start up, shut down, or operation in
high temperatures, this range can go higher.
3 Compound Gage (SUCTION PRESSURE). The pressure gage will indicate more than 15 psi (104 kPa) or less
than 0 psi (0 kPa) if a fault occurs in the refrigeration system At start up, shut down, or operation m 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
m the refrigeration system causes the pressure of the refrigerant gas leaving the compressor to exceed 300
psi (2070 kPa). Push the reset button to reset the dual pressure control switch.
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 m 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 1/4 up the port or will show the oil foaming if there is a fault m the refrigeration system.
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