TM 9-4110-256-14
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 15 F (-9
C) above or below the remote bulb thermostat setting if a fault occurs in the temperature control x,
system.
2
Pressure Gage (DISCHARGE PRESSURE). The pressure gage 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 Gage (SUCTION PRESSURE). The compound gage will indicate more than 15 psi (103.5
kPa) or less than 0 psi (O kPa) if a fault occurs in the refrigeration system. At start up, 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). 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 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
less than 1/4 up the port or will show the oil foaming if there is a fault in the refrigeration system.
2-4