Start-Up, Rtu- - Mp Control - Bryant 548J Service And Maintenance Instructions

Internal Wiring
Check all electrical connections in unit control boxes.
Tighten as required.
Refrigerant Service Ports
Each unit system has two
valves) service ports: one on the suction line, and one on
the compressor discharge line. Be sure that caps on the
ports are tight.
Compressor Rotation
On 3- - phase units with scroll compressors, it is important
to be certain compressor is rotating in the proper
direction. To determine whether or not compressor is
rotating in the proper direction:
1. Connect service gauges to suction and discharge
pressure fittings.
2. Energize the compressor.
3. The suction pressure should drop and the discharge
pressure should rise, as is normal on any start- - up.
If the suction pressure does not drop and the discharge
pressure does not rise to normal levels:
1. Note that the evaporator fan is probably also rotating
in the wrong direction.
2. Turn off power to the unit and install lockout tag.
3. Reverse any two of the unit power leads.
4. Re- - energize to the compressor. Check pressures.
The suction and discharge pressure levels should now
move to their normal start- - up levels.
NOTE: When the compressor is rotating in the wrong
direction, the unit will make an elevated level of noise
and will not provide cooling.
Cooling
Set space thermostat to OFF position. To start unit, turn on
main power supply. Set system selector switch at COOL
position and fan switch at AUTO. position. Adjust
thermostat to a setting below room temperature.
Compressor starts on closure of contactor. (08D–09D:
Second stage of thermostat will energize Circuit 2
contactor, start Compressor 2.)
Check unit charge. Refer to Refrigerant Charge section.
Reset thermostat at a position above room temperature.
Compressor will shut off. Evaporator fan will shut off
after a 30- - second delay.
To shut off unit - - set system selector switch at OFF
position. Resetting thermostat at a position above room
temperature shuts unit off temporarily until space
temperature exceeds thermostat setting.
Heating
To start unit, turn on main power supply.
Set system selector switch at HEAT position and set
thermostat at a setting above room temperature. Set fan at
AUTO position.
1
/ " SAE flare (with check
4
First stage of thermostat energizes compressor heating
(08D–09D: both compressors will start). Second stage of
thermostat energizes electric heaters (if installed). Check
heating effects at air supply grille(s).
If electric heaters do not energize, reset limit switch
(located on supply- - fan scroll) by pressing button located
between terminals on the switch.
To shut off unit - - set system selector switch at OFF
position. Resetting thermostat at a position below room
temperature temporarily shuts unit off until space
temperature falls below thermostat setting.
Ventilation (Continuous Fan)
Set fan and system selector switches at ON and OFF
positions, respectively. Supply fan operates continuously
to provide constant air circulation.
START- - UP, RTU- - MP CONTROL
Field Service Test, explained below, will assist in proper
start- - up. Configuration of unit parameters, scheduling
options, and operation are also discussed in this section.
Field Service Test
The Field Service Test function can be used to verify
proper operation of compressors, heating stages, indoor
fan, power exhaust
dehumidification. Use
recommended at initial system start up and during
troubleshooting.
Field Service Test mode has the following changes from
normal operation:
S Outdoor air temperature limits for cooling circuits,
economizer, and heating are ignored.
S Normal compressor time guards and other staging delays
are ignored.
S The status of Alarms (except Fire and Safety chain) is
ignored but all alerts and alarms are still broadcasted on
the network.
Field Service Test can be turned ON/OFF at the unit
display or from the network. Once turned ON, other
entries may be made with the display or through the
network. To turn Field Service Test on, change the value
of Test Mode to ON, to turn Field Service Test off, change
the value of Test Mode to OFF.
NOTE: Service Test mode is password protected when
accessing from the display. Depending on the unit model,
factory- - installed options, and field- - installed accessories,
some of the Field Service Test functions may not apply.
The independent outputs (IndpOutputs) submenu is used
to change output status for the supply fan, economizer,
and Power Exhaust. These independent outputs can
operate simultaneously with other Field Service Test
modes. All outputs return to normal operation when Field
Service Test is turned off.
The Cooling submenu is used to change output status for
the individual compressors and the dehumidification relay.
Compressor starts are not staggered. The fans and heating
service test outputs are reset to OFF for the cooling
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fans, economizer,
of Field Service Test
and
is