First Co WCX12 Replacement Units - Manual (Page 4)

Then check the sub-cooling of the liquid refrigerant at the outdoor unit to insure a proper liquid seal is present at the expansion
valve. This measurement should be made 2 to 4 inches above the WCX12 cabinet by measuring the temperature of the liquid line and
the high side pressure. At outdoor conditions between 80 to 95 degrees the system should be charged to a sub-cooling level of 6 to 10
degrees at the outdoor unit. If it is necessary to add charge it must be added in the liquid phase into the suction line of the WCX12.
Use a commercial metering device to add liquid to the system without damaging the compressor. This charge will permit the expan-
sion valve to operate properly at the factory setting.
To increase sub-cooling increase refrigerant charge. To decrease sub-cooling decrease refrigerant charge. If adding refrigerant
raises both the pressure and the temperature of the liquid refrigerant then the system is over charged.
ELECTRICAL POWER SUPPLY
The electric installation must be in accordance with the National Electric Code and any local codes or ordinances. Use a separate
branch circuit for this unit and locate a disconnecting means within sight of the unit and readily accessible for service personnel.
Minimum circuit ampacity and maximum circuit breaker size information is shown on the unit nameplate. Use copper conductors
only. NOTE: A Compressor Time Delay Relay may be required and will need to be fi eld installed if rapid cycling of the compressor
occurs.
WARNING: Disconnect all power to unit before servicing fi eld wires or removing control package. The disconnect
(when used) does not disconnect power to the line side of the disconnect, but does allow safe service to all other parts
of the unit. If the unit does not have a disconnect, disregard the foregoing. Instead, make sure that a disconnecting
means is within sight from, and is readily accessible from, the unit. Disconnect all power to the unit before performing
any maintenance or service on it. Failure to follow this WARNING can cause electrical shock, fi re, personal injury or
death.
CAUTION: Operation of unit on improper line voltage constitutes abuse and could affect unit reliability and opera-
tion. See unit rating plate. Do not install a system where voltage or phase imbalance may fl uctuate above or below
permissible limits. If low voltage conditions exist, use of Start Assist Device may be required.
THERMOSTAT WIRING
Run a thermostat cable of at least 2 - wires between the condensing unit and the indoor unit. Pigtail leads are provided at the con-
densing unit. Make connections using wire nuts and tape for security. (See fi gure 3)
SERVICE & MAINTENANCE
Keep the inside of the unit clean and be certain the drain holes in the base of the pan are open to assure rain drainage from the unit.
Keep the condenser coil clean. Any restriction of the condenser air fl ow can seriously effect the system performance.
Maintenance Updates
For a current copy of the Maintenance Program log onto www.fi rstco.com and look under “Product Information”.
THERMOSTAT WIRING
24VAC - CLASS 2
POWER SUPPLY WIRING
FIGURE 3 FIGURE 2
CONTACTOR
WALL
MOUNTED
THERMOSTAT
FAN COIL
UNIT
CONTACTOR
* IF HEATING IS REQUIRED
*
208-230V
1PH - 60HZ
GND
DISCONNECT
R R
Y Y
G G
W W
GND
LUG