Installation, Operation and Maintenance Manual : 036-1011(0806)
Page 20
protector will open to shut down the compressor. The UCB
incorporates features to minimize compressor wear and
damage.
An anti short cycle delay (ASCD) is utilized to prevent
operation of a compressor too soon after its previous run.
Additionally, a minimum run time is imposed any time a
compressor is energized.
The ASCD is initiated on unit start up and on any compressor
reset or lock out.
FLASH CODES
The UCB will initiate a flash code associated with errors
within the system. Refer to UNIT CONTROL BOARD FLASH
CODES Table 11.
RESET
Remove the call for cooling, by raising thermostat setting
higher than the conditioned space temperature. This resets
any pressure or freezestat flash codes.
ELECTRIC HEATING SEQUENCE OF OPERATIONS
The following sequence describes the operation of the
electric heat section. Two-stage heating (Heaters MUST use
a two stage thermostat) :
a. Upon a call for first-stage heat by the thermostat, the
heater contactor will be energized. After completing the
specified fan on delay for heating, the UCB will energize
the blower motor. If the second stage of heat is required,
second heater contactor will be energized. After
completing the specified fan on delay for heating, the
UCB will energize the blower motor.
b. The thermostat will cycle the electric heat to satisfy the
heating requirements of the conditioned space.
HEATING OPERATION ERRORS
TEMPERATURE LIMIT
If the UCB senses zero volts from the high temperature limit,
the indoor blower motor is immediately energized. This limit
is monitored regardless of unit operation status, i.e. the limit
is monitored at all times. If the temperature limit opens three
times within one hour, it will lock on the indoor blower motor
and a flash code is initiated (See Table 11).
SAFETY CONTROLS
The unit control board monitors the temperature limit switch
of electric heat units. The control circuit includes the following
safety controls :
Temperature Limit Switch (AUTO)
This control is located inside the heater compartment and is
set to open at 120°F. It resets automatically. The limit switch
operates when a high temperature condition, caused by
inadequate supply air flow occurs, thus shutting down the
heater and energizing the blower.
RESET
Remove the call for cooling, by raising thermostat setting
higher than the conditioned space temperature. This resets
any pressure or freezestat flash codes.
FLASH CODES
The UCB will initiate a flash code associated with errors
within the system. Refer to UNIT CONTROL BOARD FLASH
CODES Table 11.
START UP (COOLING)
PRESTART CHECK LIST
After installation has been completed :
1. Check the electrical supply voltage being supplied. Be
sure that it is the same as listed on the unit nameplate.
2. Set the room thermostat to the on position.
3. Turn unit electrical power on.
4. Set the room thermostat fan switch to on.
5. Check indoor blower rotation.
If blower rotation is in the wrong direction. Refer to
Phasing Section in general information section.
Check blower drive belt tension.
Check bearing lubrication. If it requires lubrication,
grease it.
6. Check the unit supply air (CFM).
7. Measure evaporator fan motor amp draw.
8. Set the room thermostat fan switch to off.
9. Turn unit electrical power off.
OPERATING INSTRUCTIONS
1. Turn unit electrical power on.
2. Set the room thermostat setting to lower than the room
temperature.
3. First stage compressors will energize after the built in
time delay (five minutes).
4. The
2
nd
, 3
rd
and 4
th
stage of the thermostat will energize
the respective compressors (if needed).
POST START CHECK LIST
1. Verify proper system pressures for both circuits.
2. Measure the temperature drop across the evaporator
coil.
3. Measure the system Amperage draw across all legs of 3
phase power wires.
4. Measure the condenser fan amp draw.
