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Manual

15

BC251686497767en-US0801

Sequence of operation – Field wiring

Sequence of operation

Refrigeration Cycle

1.  Defrost timer is powered by the condensing 

unit, connecting the supply to terminal “1” and 
“N”.

2.  The fan delay and the defrost termination 

thermostat is closed in the fan delay position 
and open in the defrost termination position. 
The evaporator fan(s) run continuously. 

3.  The defrost heaters are off during refrigeration 

cycle.

4.  The room thermostat closes when the 

temperature rises above the desired setting.

5.  The liquid line solenoid valve(LSV) gets 

energized and opens to allow the liquid 
refrigerant to flow through the evaporator.

6.  The low-pressure control switch closes when the 

suction pressure rises above the cut-in setting.

7.  The compressor contactor gets energized and 

supply power to allow the compressor and 
condenser fan to run.

8.  The room temperature gradually decreases to 

the desired temperature.

9.   Once the desired temperature is attained, the 

thermostat opens and the liquid line solenoid 
closes, it will in turn stop the refrigerant flow 
through the evaporator.

10.  Suction pressure decreases and the 

compressor contactor opens when the 
pressure drops below the cut-out setting on 
the low-pressure control. The compressor and 
condenser fan stop running.

11.  This cycle is repeated as many times as 

necessary to satisfy the room thermostat. 

12.  Frost may form on the evaporator coil until the 

defrost cycle is initiated.

Defrost Cycle

1.  The defrost cycle starts automatically by the 

timer at predefined intervals. Typical settings 
are between two and four defrost cycles per day 
for freezers. For heavier frost loads additional 
settings may be required.

2.  Contacts “2” to “4” opens in the defrost timer and 

disconnects the circuit to the room thermostat, 
liquid line solenoid, and evaporator fan motors. 
This will lead the compressor to pump down 
and shut-off. At the same time, Contacts “1” 

to “3” closes in the timer and it will allow the 
defrost heater to start through the heater 
contactor. 

3.  The defrost heaters rise the temperature of the 

coil to 32˚F triggering the frost to melt of the 
coil.

4.  When the coil temperature rises to 45˚F to 55˚F, 

the cycle limit switch closes and it energizes 
the Liquid line solenoid valve to allow the 
refrigeration cycle to begin again.

Summary of Contents for OP-HJZM

Page 1: ...Installation and maintenance condensing unit manual OP HJZM HNXM HRXM LNYM LRYM LJHM Manual http cc danfoss com...

Page 2: ...e of the condensing unit must be carried out by qualified personnel only Follow these instructions and best practices on refrigeration engineering during installation commissioning maintenance and ser...

Page 3: ...t or pallet jack for handling Use appropriate and safe lifting equipment Store and transport the unit in an upright position Store the unit between 30 F and 120 F Don t expose the packaging to rain or...

Page 4: ...erial Use clean and dehydrated system components The suction piping connected to the compressor must be flexible in 3 dimensions to dampen vibrations Furthermore piping has to be done in such a way th...

Page 5: ...applied to this product it causes transformation of characteristics or the destruction Operation will become unstable when using other than sine waves for the power supply In this case proper control...

Page 6: ...Such as snow or freezing Check if a line to line short circuit is detected at a connection point of the fan motor It is recommended to protect the circuit with a thermal relay or circuit protector No...

Page 7: ...intenance Switch off the system and isolate the main power supply Ensure that power supply cannot be switched on during installation All electrical components must be selected as per local standards a...

Page 8: ...rify that all electrical connections are properly fastened and in compliance with local regulations When a crankcase heater is required it must be energized at least 12 hours before initial start up a...

Page 9: ...ctions are still adequately fastened Keep the unit clean and verify the absence of rust and oxidation on the unit components tubes and electrical connections The condenser must be checked at least onc...

Page 10: ...47 4 16 5 7 8 1 2 HRXM0500 2 28 8 49 4 31 5 7 8 1 2 HRXM0600 2 28 8 49 4 31 5 7 8 1 2 HRXM0700 2 28 8 49 4 31 5 7 8 1 2 HRXM0750 2 39 1 61 2 31 5 1 1 8 5 8 HRXM1000 2 39 1 61 2 31 5 1 1 8 5 8 Unit Di...

Page 11: ...1 8 X 7 8 W D H 2X Knockout 7 8 Liquid Line C L C L Suction Line 2X Double Knockout 1 1 8 X 7 8 W H D 2X Knockout 7 8 C L Suction Line Liquid Line C L 2X Double Knockout 1 1 8 X 7 8 W D H 2X Knockout...

Page 12: ...BC251686497767en US0801 Electrical wiring diagrams Wiring Diagram 119 8312 Wiring Diagram 119 8313 Electrical Code N HJZM0150 HNXM0200 0400 HRXM0500 LJHM0150 0200 Electrical Code Q HNXM0200 0400 HRXM...

Page 13: ...51686497767en US0801 Electrical wiring diagrams X 4 2 1 N 3 N O LOAD N C LOAD Wiring Diagram 119 8315 Wiring Diagram 119 8493 Electrical Code Q HJZM0150 LJHM0150 0200 Electrical Code Q LNYM0400 0500 L...

Page 14: ...Manual 14 BC251686497767en US0801 Electrical wiring diagrams Wiring Diagram 119 8640 Wiring Diagram 119 8641 Electrical Code R HRZM0600 1000 Electrical Code R LRYM0600 0800...

Page 15: ...op the refrigerant flow through the evaporator 10 Suction pressure decreases and the compressor contactor opens when the pressure drops below the cut out setting on the low pressure control The compre...

Page 16: ...ensions Length Height in mm in mm HJXM0150 0200 LJHM0150 0300 26 660 19 480 HJXM0200 0300 29 740 22 550 LNYM0400 0500 HJXM0350 0400 31 780 27 700 HRXM0500 0700 LRYM0600 0800 46 1170 28 720 HRXM0750 10...

Page 17: ......

Page 18: ...erter Scrolls Danfoss Turbocor Compressors Danfoss Scrolls Danfoss Optyma Condensing Units Danfoss Maneurop Reciprocating Compressors BC251686497767en US0801 Danfoss DCS CC 2019 11 Our products can be...

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