Installation, Operation and Maintenance Manual
C13-Series
18
Subject to change without notice.
10.20-IM (0818)
Belts
Drive belts should be examined periodically for wear and
for correct tension� Belts that are too tight cause bearing
wear while belts that are too loose cause slippage� If the
midpoint (midway between the blower and motor shaft) of
the belt is pressed inward, there should be about 1/2" to
a 1" of deflection when the belt is properly tensioned. Belt
tension can be adjusted by means of the adjusting bolt,
which requires loosening of a nut to move the motor and
change belt position�
Refrigerant Systems
All United CoolAir systems contain a liquid line sightglass�
If bubbles appear in the sightglass, the system is either
undercharged with refrigerant or there may be a restriction in
the liquid line upstream of the sightglass� However, bubbles
will appear every now and then in units with the hot gas
bypass option� Bubbles will also appear upon compressor
start up but normally clear to pure liquid after a few minutes
of operation�
The sightglass contains a moisture indicator which changes
color when moisture is present in the system� This indicator
is the circular dot in the center of the sight glass� If the color
of this indicator is green, the refrigerant is normal� When
the indicator is yellow, an abnormal condition exists such
as moisture within the refrigerant circuit� If an abnormal
appearance exists, servicing is required� See Figure 10 for
unit charges�
INFORMATION
NOTE: After installation and during
equipment start-up, the sight glass may
appear pink or purple� This occurs during
prolonged periods of non-operation and
should turn blue after several hours (up to
12) of operation�
Evaporator And Air-Cooled
Condenser Coils
Check semi-monthly the condition of the face of both the
evaporator and condenser coils�
A dirty condenser coil will cause high condensing pressures,
resulting in higher power consumption and possibly system
shut-down by high-pressure
safety control� A dirty evaporator coil will reduce unit capacity
and eventually will cause shut-down by the low pressure
safety control�
Minimum Service Access
All Service and Maintenance access is through both sides of
the unit. 36" clearance is required.
Application Data
208 / 230
460
Voltage Variation
187 / 253
414 / 504
Cooling
(Air Over Evap.)
DB (Min./Max.)
45 / 120
WB (Min./Max.)
57 / 72
Heat Pump
(Air Over ID Coil)
DB (Min./Max.)
50 / 80
Water-Cooled
GPM/Ton (Min./Max.)
2.5 / 3.5
Leaving Water Temp.
(Min./Max.)
60 / 115
Hard Start Kit
A start assist device is utilized on all single-phase units� The
purpose of this device is to assist the compressor in starting
under low voltage conditions�
A capacitor in conjunction with a Positive Temperature
Coefficient (PTC) relay is installed across the run and
start windings of the motor� The PTC device utilizes a
ceramic element with a predictable thermal response to
the introduction of electric current� When the compressor is
called upon to start, the start capacitor provides a voltage
boost to the start winding of the motor and causes the motor
to turn� As the starting current is introduced across the start
windings, the PTC element begins to warm� When the PTC
device reaches approximately 250°F (corresponding to 0�6-
0�8 seconds), the resistance in the element increases and
creates an open switch that releases the start winding from
the circuit and the motor continues to run� If the compressor
does not start before the device heats to 250°F, it will not
start until the PTC device cycles through a cool-down
period (usually 2-3 minutes)� A compressor off-cycle timer is
included in the electrical circuit for this purpose�
The time delay relay also helps the refrigerant system
pressures to equalize at the end of the run cycle� This helps
the compressor during the starting process in that it is not
attempting to start against a high discharge pressure�
INFORMATION
The installer should verify that this timer is
set for 3 or more minutes�
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