23
MAINTENANCE
Cleaning
The unit should be thoroughly cleaned inside and out. Frequency
of cleaning will depend on unit location and area conditions.
Drains must be kept free of dirt and trash. Coils can be cleaned
with a stiff brush or vacuum cleaner. Coil can be reached through
access panels.
Inspection
Check coil baffles for tight fit to prevent air from bypassing the
coil. Check panels for air leakage, particularly those sealing the
fan and coil compartments. Check for loose electrical connections,
proper refrigerant charge, and refrigerant piping leaks.
Condensate Drain
The drain pan and trap should be cleaned at least twice per year.
After cleaning, test the condensate drain for proper operation by
pouring a bucket of water into the condensate drain pan. The water
should flow out immediately and evenly.
Checking System Charge
NOTE: Condenser and evaporator airflow must be properly set
before checking system charge.
The 50XCR units are shipped with full operating charge. If re
-
charging is necessary:
1. Insert thermometer bulb in insulating rubber sleeve on liquid
line near filter drier. Use a digital thermometer for all tem
-
perature measurements. DO NOT use a mercury or dial-type
thermometer.
2. Connect refrigerant pressure gage to discharge line near
compressor.
3. After unit condition have stabilized, read head pressure on
discharge line gage.
NOTE: Operate unit a minimum of 15 minutes before check
-
ing charge.
4. From standard Pressure-Temperature chart for R-410A, find
equivalent saturated condensing temperature.
5. Read liquid line temperature on thermometer; then subtract
from saturated condensing temperature. The difference
equals subcooling temperature.
6. Compare the subcooling temperature with the normal tem
-
perature listed in Table 15. If the measured liquid line tem
-
perature does not agree with the required liquid line
temperature, ADD refrigerant to raise the temperature or
REMOVE refrigerant (using standard practices) to lower the
temperature (allow a tolerance of ± 3°F).
Example:
Head pressure (from gage) 416.4 psig
Saturated condensing temp (from chart) 120°F
Liquid line temp (from thermometer) 100°F
Subcooling (by subtraction) 20°F
Table 15 —
Subcooling Temperature
*Saturated condensing temperature at compressor minus liquid line
temperature.
NOTE: Do not vent or depressurize unit refrigerant to atmosphere.
Remove and recover refrigerant following accepted practices.
Evaporator-Fan Motor Removal
1. Shut off unit main power supply. Lock out power supply and
tag disconnect locations.
2. Loosen bolts on mounting bracket so that fan belt can be
removed.
3. Disconnect motor power wires from motor terminals.
4. Remove the 4 motor mounting bolts from bottom of motor.
5. Remove motor. Rest motor securely on a high platform such
as a step ladder. Do not allow motor to hang by its power
wires.
Pressure Relief Device
All units are equipped with a fusible-plug type safety relief device
on the refrigerant tubing. The relief setting is 210°F.
Current Protection Device
All units are equipped with a current-sensing lockout relay on
each circuit. This device will lock out the compressor after any
safety trip (high-pressure switch, low-pressure switch, or internal
overload of the compressor) for 5 minutes. Check reason for lock
-
out before resetting the device. To reset, turn the thermostat sys
-
tem switch to OFF, then back to COOL position.
High and Low-Pressure Switches
The high-pressure switch is located on the compressor discharge
line. The low-pressure switch is located on the suction line.
Oil Charge
All units are factory charged with oil (see Table 2 for compressor
model number). It is not necessary to add oil unless the compres
-
sor is removed from the unit. If additional oil is needed, do not use
mineral oils. Only synthetic oils are satisfactory.
UNIT 50XCR
SUBCOOLING*
06
20°F
08
17°F
12,14
21°F
16
18°F
24
25°F
WARNING
To prevent personal injury, wear safety glasses and gloves
when handling refrigerant. Do not overcharge system — this
can cause compressor flooding.
CAUTION
Before attempting to remove fan motors or motor mounts,
place a piece of plywood over evaporator coils to prevent coil
damage.
