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5-Reversing Valve L1 and L2
A refrigerant reversing valve with a 24 volt solenoid coil is
LDT units. The reversing valve is connected in the vapor
line of the refrigerant circuit. The reversing valve coil is
energized during cooling demand and during defrost.
Reversing valve L1 and L2 are controlled by the M4 con-
troller in response to cooling demand or by defrost.
6-Defrost Pressure Switch S46 and S104
The defrost pressure switch S46 and S104 are auto-reset
SPST N.C. pressure switches which open on a pressure
rise. All LDT units are equipped with these switches. The
switches are located on the discharge line. S46 and S104
are wired in series with the CMC1 control board.
+ 10 psig (3102 +
the appropriate switch opens. The switches automatically
reset when pressure in the suction line drops to 300 + 20
psig (2068 +
7-Defrost Temperature Switch S6 and S9
Defrost thermostat switches S6 and S9 have S.P.S.T. N.O.
contacts which close on a temperature fall (initiating de-
distributor assembly at the inlet to the outdoor coil. The
switch monitors the outdoor coil suction temperature to
determine when defrost is needed. When the outdoor coil
+ +
the switch closes (initiating defrost after minimum run time
++
8-Filter Drier (all units)
each refrigerant circuit at the exit of each condenser coil
-
nants and moisture from the system.
9-Condenser Fan Motors B4, B5, B21
directly to 230VAC power but do not operate until a pulse
M4 controller. All outdoor fans will run at the same speed
when the appropriate PWM signal is received. The fans
may be removed for servicing and cleaning by removing
the fan grilles.
10-Crankcase Heaters HR1, HR2
Heater HR1 is installed around compressor B1 and heater
HR2 is installed around compressor B2. Crankcase heat-
er wattage varies by compressor manufacturer.
11-Temperature Sensors RT46, RT47, RT48 & RT49
Units are equipped with four factory-installed thermistors
-
ant circuit.
The thermistors provide the Unit Controller with constant
-
frigeration circuit. These temperatures are used as feed-
back in certain modes of unit operation.
FIGURE 6 proper locations.
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