520413-BIM-A-0209
30
Johnson Controls Unitary Products
Sequence of Operation
Continuous Blower
By setting the room thermostat to "ON," the low voltage control
circuit from the "R" to "G" is completed and the supply air
blower will operate continuously.
Intermittent Blower
With the room thermostat fan switch set to "AUTO" and the
system switch set to either the "AUTO" or "HEAT" settings, the
blower is energized whenever a cooling or heating operation is
requested. The blower is energized after any specified delay
associated with the operation.
Cooling Sequence of Operation
Single Stage Indoor Unit Matched with a Single Stage
Condensing Unit
When the thermostat calls for cooling, the low voltage control
circuit from "R" to "Y1" and "G" is completed. The Simplicity™
control board activates cooling by energizing the compressor
and condenser fans of the condensing unit. After completing
the specified fan on delay for cooling, the Simplicity™ control
board will energize the indoor blower motor.
Two Stage Indoor Units Matched with a Two Stage
Condensing Unit
When the thermostat calls for the first stage of cooling, the low
voltage control circuits from "R" to "Y1", "G1" and "S1" is
completed. The Simplicity™ control board activates the first
stage of cooling by energizing the System #1 liquid line
solenoid of the indoor unit and the System #1 compressor and
condenser fans of the condensing unit. After completing the
specified fan on delay for cooling, the Simplicity™ control board
will energize the indoor blower motor (Note: Both Terminals G1
and G2 need to be jumped together).
When the thermostat calls for the second stage of cooling, the
low-voltage control circuit from "R" to "Y2" and "S2" is
completed. The Simplicity™ control board activates the second
stage of cooling by energizing System #2 liquid line solenoid of
the indoor unit and the System #2 compressor and condenser
fans of the condensing unit.
If there is an initial call for both stages of cooling, the
Simplicity™ control board will delay energizing compressor #2
by 30 seconds in order to avoid an excessive power rush.
Two Single Stage Indoor Units Matched with a Two Stage
Condensing Unit
Two appropriately sized indoor units can operate with a single,
4-pipe condensing unit. Each indoor unit must be controlled by
a single-stage thermostat. One thermostat will connect to Y1 on
the condensing unit Simplicity™ control board and the other
thermostat will connect to Y2.
The jumper between G1 and G2 must be removed on the T2
terminal block. Both G1 and G2 will provide 24V signals to
operate their respective indoor fan motors.
When a thermostat calls for cooling, the Simplicity™ control
board energizes the appropriate compressor and condenser
fans. Fan #1 will start immediately upon the call for cooling.
However, the control circuit for fan #2 is equipped with a fan
cycling switch that operates the fan in the 180-280 psig head
pressure range.
When the second thermostat calls for cooling, the Simplicity™
control board energizes the appropriate compressor and
condenser fans. Fan #3 will start immediately upon the call for
cooling. However, the control circuit for fan #4 is equipped with
a fan cycling switch that operates the fan in the 180-280 psig
head pressure range.
Once a call for cooling has been satisfied, the Simplicity™
control board will de-energize the respective Y1 or Y2 signal. If
the associated compressor has satisfied its minimum run time,
it is de-energized along the system's condenser fans. If both
calls for cooling have been satisfied, the Simplicity™ control
board will de-energize the other signal. If the associated
compressor has satisfied its minimum run time, it and its
associated condenser fans are de-energized. Otherwise, the
unit operates each compressor and condenser fans until the
ASCD has elapsed.
The appropriate blower is stopped following the completion of
the fan off-delay cycle.
Maintenance
Filters must be cleaned or replaced as often as necessary to
assure good airflow and filtering action.
To remove filters through the side of the unit, remove the solid
side panel on the piping end.
To remove the filters from the front of the unit, open access
panel. The filters can be lifted out through the access panel.
The drain pan should be inspected regularly to assure proper
drainage.
Blower bearings and motor bearings are permanently
lubricated.
