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EVAPORATORS
All evaporator units should be checked once a month or more often for proper defrosting because the amount
and pattern of frosting can vary greatly. It is dependent on the coil temperature, the temperature of the room,
the type of product being stored, how often new product is brought into the room and the percentage of time
the door to the room is open. It may be necessary to periodically change the number of defrost cycles or
adjust the duration of defrost.
CONDENSING UNITS / EVAPORATORS
Under normal usage conditions, maintenance should cover the following items at least once every 6 months:
1. Check and tighten ALL electrical connections.
2. Check all wiring and insulators.
3. Check contactors for proper operation and for worn contact points.
4. Check all fan motors. Tighten motor mount bolts and nuts and tighten fan set screws.
5. Clean the condenser coil surface.
6. Check the refrigerant and oil level in the system.
7. Check the operation of the control system. Make certain all safety controls are operating properly.
8. Check that all defrost controls are functioning properly.
9. Clean the evaporator coil surface.
10. Clean the drain pan and check the drain pan and drain line for proper drainage.
11. Check the drain line heater for proper operation, cuts and abrasions.
12. Check and tighten all flare connections.
Check-Out & Start-Up
After the installation has been completed, the following points should be covered before the system is placed
in operation:
(a) Check all electrical and refrigerant connections. Be sure they are all correct and tight.
(b) Check voltage taps on transformer. The transformer is shipped wired to 240 voltage tap/connection. If
your supply voltage is 208 volt systems, change to 208 voltage tap.
(c) Check setting of time delay relay for low pressure switch in condensing unit. It should be set at one
minutes (the second marker).
(d) Check high and low pressure controls, pressure regulating valves, oil pressure safety controls, and all
other safety controls and adjust them, if necessary.
(e) On freezers only, check the low pressure switch setting. It must be set to 0 PSIG cut out, 10 PSIG cut
in, to allow start and operation, especially in cold ambients.
(f) Liquid line should always be insulated.
(g) Wiring diagrams, instruction bulletins, etc. attached to the condensing units should be read and filed for
future reference.
(h) All fan motors on air cooled condensers, evaporators, etc. should be checked for proper rotation. Fan
motor mounts should be carefully checked for tightness and proper alignment.
(i) Observe system pressures during charging and initial operation. Do not add oil while the system is
short of refrigerant unless oil level is dangerously low.
(j) Continue charging until system has sufficient refrigerant for proper operation. Do not overcharge.
Remember that bubbles in a sight glass may be caused by a restriction as well as a shortage of
refrigerant.
(k) Do not leave unit unattended until the system has reached normal operating conditions and the oil
charge has been properly adjusted to maintain the oil level at the center of the sight glass.
(l) At initial start-up, the system may cycle off at 2 minutes and display a low superheat error, then restart
itself. This cycle may be repeated a few times. Do not shut the system off. Let the system run, as it may
take a few cycles for the electric expansion valve to attain the correct setting for the desired superheat.
CAUTION: Extreme care must be taken in starting compressors for the first time after system charging. At
this time, all of the oil and most of the refrigerant might be in the compressor creating a condition which could
cause compressor damage due to slugging. Activating the crankcase heater for 24 hours prior to start-up is
recommended. If no crankcase heater is present, then directing a 500 watt heat lamp or other safe heat
source on the lower shell of the compressor for approximately thirty minutes will be beneficial in eliminating
this condition which might never reoccur.
Preventive Maintenance