998659-YIM-C-0614
46
Johnson Controls Unitary Products
Limit Switch (Ls)
This control is located inside the heater compartment and is set
to open at the temperature indicated in the Electric Heat Limit
Setting Tables 20 and 21. 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.
Flash Codes
The UCB will initiate a flash code associated with errors within
the system. Refer to UNIT CONTROL BOARD FLASH CODES
Table 23.
Reset
Remove the call for heating by lowering the thermostat setting
lower than the conditioned space temperature.This resets any
flash codes.
Electric 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 22 for the required electric
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 information section.
Check blower drive belt tension.
6.
Check the unit supply air (CFM).
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.
NOTE:
Prior to each cooling season, the crankcase heaters
must be energized at least 10 hours before the system
is put into operation.
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 evaporator coil.
Charging The Unit
All XP units use Thermal Expansion Devices. Charge the unit to
10° subcooling.
Table 21: Electric Heat Limit Setting 50” Cabinet
UNIT (TONS)
VOLTAGE
HEATER
kW
LIMIT
SWITCH
OPENS °F
XP078, 090, 102
(6.5, 7.5, 8.5)
208/230
9
150
18
150
24
150
34
150
XP 120, 150
(10, 12.5)
18
150
24
150
34
150
54
130
XP078, 090, 102
(6.5, 7.5, 8.5)
480
9
150
18
150
24
150
34
150
XP 120, 150
(10, 12.5)
18
150
24
150
34
150
54
130
XP078, 090, 102
(6.5, 7.5, 8.5)
600
9
150
18
150
24
150
34
150
XP 120, 150
(10, 12.5)
18
150
24
150
34
150
54
130
Table 22: Electric Heat Anticipator Setpoints
SETTING, AMPS
W1
W2
0.13
0.1
