Nor-Lake Refrigeration Systems - Manual (Page 18)

09/14 Rev. E 101628 18
OPERATIONAL CHECK OUT
Note: It is recommended that the system be checked out by a qualified refrigeration mechanic even
when the system is provided with pre-charged line sets.
The cold room pull down to normal operation will take some time depending on operating conditions
and room size. When normal operation is achieved, a thorough check of the entire system
operation must be made as follows:
1. Check the compressor high side and low side pressures. If not within the system design limits,
determine why and take corrective action.
2. Check the liquid line sight glass for full charge and moisture indication.
3. Check the expansion valve for proper super heat setting. The feeler bulb must be properly
located and in positive contact with the suction line.
4. Using suitable instruments, carefully check the line voltage and amperage at the compressor
terminals. The voltage must be within ±10% of the voltage listed on the compressor nameplate
for accessible hermetic compressors. If high or low voltage is indicated, notify the power
company. If amperage is excessive, immediately determine the cause and take corrective
action. On three phase compressors, check to see that a balanced load is drawn by each
phase.
5. Recheck all electrical connections for tightness.
6. Check high-pressure control for proper operation. The cut out pressure is 440 psi for R-
404A systems. On water-cooled condensing systems the cut out pressure for R-404A is
380 psi. On air cooled systems, check as follows:
a. Disconnect condenser fan motor(s) or block the condenser inlet air.
b. Watch the high pressure gauge for the cut-out point.
c. Recheck all safety and operating controls for proper operation and adjust if
necessary.
7. Observe oil level in compressor crankcase sight glass, accessible hermetic models only, and
add oil as needed to bring level to center of the sight glass.
8. All fan motors on air-cooled condensers, evaporators, etc. should be checked for proper rotation
and motor mounts checked for tightness and alignment.
9. Check the system operational sequence. Check freezer defrost controls for initiation,
termination, and length at defrost period. Check temperature control operation as related to
room temperature and system pump down.
10. Check the drain line on the unit cooler for proper drainage and ensure water will not accumulate
in the drain pan. Check the freezer drain line heater for proper operation.
11. Check all refrigerant tubing, capillary tubes and conduit for vibration or rubbing. Secure or
isolate as required.
12. Replace all valve caps and secure all guards and covers.
13. Fill out the system reference data found on the last page of this manual and deliver to the
owner along with all wiring diagrams, instruction manuals, etc. collected earlier. The
owner should file all of this information for future reference.
14. A preventive maintenance schedule should be set up with or for the owner as soon as possible
after start up to maintain equipment integrity and efficiency.
SEQUENCE OF OPERATION
High/Medium Temperature Systems:
35° and warmer rooms utilize off cycle defrost. The room temperature control which senses
evaporator return air opens upon room temperature reaching the control cut out point. This action
causes the liquid solenoid to close, stopping refrigerant flow to the expansion valve. The
condensing unit continues to run until the low side pressure reaches the low-pressure control cut
out set point. The system is now pumped down with most of the refrigerant isolated in the
receiver/condenser and the condensing unit stops. The unit cooler fan(s) continue operation,
circulating room temperature air, which is above freezing, through the evaporator causing the