66396-YIM-C-1004
Unitary Products Group
31
FLASH CODES
The UCB will initiate a flash code associated with
errors within the system. Refer to UNIT CONTROL
BOARD FLASH CODES Table 21.
RESET
Remove the call for heating by lowering the thermostat
setting lower than the conditioned space temperature.
This resets any flash codes.
HEAT ANTICIPATOR SETPOINTS
It is important that the anticipator setpoint be correct.
Too high of a setting will result in longer heat cycles and
a greater temperature swing in the conditioned space.
Reducing the value below the correct setpoint will give
shorter "ON" cycles and may result in the lowering of
the temperature within the conditioned space. Refer to
Table 20 for the required heat anticipator setting.
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 off 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 informa-
tion section.
•
Check blower drive belt tension.
6.
Check the unit supply air (CFM). See "CHECKING
SUPPLY AIR CFM" on Page 25.
7.
Measure evaporator fan motor's 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 second stage of the thermostat will energize
second stage compressor if needed.
POST START CHECK LIST
1.
Verify proper system pressures for both circuits.
2.
Measure the temperature drop across the evapora-
tor coil.
3.
Measure the system Amperage draw across all
legs of 3 phase power wires.
4.
Measure the condenser fan amp draw.
SHUT DOWN
1.
Set the thermostat to highest temperature setting.
2.
Turn off the electrical power to the unit.
TROUBLESHOOTING
COOLING TROUBLE SHOOTING GUIDE
TABLE 19: LIMIT CONTROL SETTING
UNIT
(Tons)
VOLTAGE
HEATER
kW
TEMPERATURE LIMIT
SWITCH 1, 2
OPENS, °C (°F)
TEMPERATURE
LIMIT SWITCH 3, 4, 5,
6 OPENS, °C (°F)
20
380/415
18
49 (120)
77 (170)
36
49 (120)
77 (170)
54
49 (120)
77 (170)
72
49 (120)
77 (170)
TABLE 20: ELECTRIC HEAT ANTICIPATOR
SETPOINTS
HEATER
KW
VOLTAGE
SETTING, AMPS
TH2
18
380/415-3-50
0.29
36
0.29
54
0.29
72
0.29
Troubleshooting of components may require
opening the electrical control box with the power
connected to the unit.
Use extreme care when
working with live circuits!
Check the unit
nameplate for the correct line voltage and set
the voltmeter to the correct range before making
any connections with line terminals.
When not necessary, shut off all electric power to
the unit prior to any of the following maintenance
procedures so as to prevent personal injury.
