430648-JIM-D-1010
22
Johnson Controls Unitary Products
2.
Move the system switch on the thermostat to the AUTO or
COOL position.
3.
Reduce the setting of the room thermostat to energize the
compressor.
4.
Check the operation of the evaporator unit per the
manufacturer’s recommendations.
5.
With an ammeter, check the compressor amps against the
unit data plate.
6.
Check for refrigerant leaks.
7.
Check for any abnormal noises and/or vibrations, and
make the necessary adjustments to correct fan blade(s)
touching shroud, refrigerant lines hitting on sheet metal,
etc.
8.
After the unit has been operating for several minutes, shut
off the main power supply at the disconnect switch and
inspect all factory wiring connections and bolted surfaces
for tightness.
Operation
Unit Control Overview
These series of condensing units, come factory equipped with
Simplicity
™ controls to monitor all unit functionality and safety
controls.
Safety Controls
The
Simplicity
™ control board incorporates features to monitor
safety circuits as well as 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 anytime a
compressor is energized to allow proper oil return to the
compressor. The ASCD is initiated on unit start-up and on any
compressor reset or lockout.
The
Simplicity
™ control board monitors the following inputs for
each cooling system:
• A high-pressure switch is factory installed to protect
against excessive discharge pressure due to a blocked
condenser coil or a condenser fan motor failure. During
cooling operation, if a high-pressure limit switch opens,
the
Simplicity
™ control board will de-energize the
associated compressors and initiate the 5-minute ASCD.
If the call for cool is still present at the end of the ASCD,
the control board will re-energize the halted compressor. If
a high-pressure switch opens three times within two hours
of operation, the Simplicity™ control board will lockout the
associated system compressors and will flash an error
code (See Table 10).
• A low-pressure switch to protect the unit against
excessively low suction pressure is standard on all
condensing units. If the low-pressure switch opens during
normal operation, the
Simplicity
™ control board will de-
energize the compressor, initiate the ASCD, and shut
down the condenser fans. On startup, if the low-pressure
switch opens, the
Simplicity
™ control board will monitor
the low-pressure switch to make sure it closes within one
minute. If it fails to close, the unit will shut down the
associated compressor and begin an ASCD. If the call for
cool is still present at the end of the anti-short cycle time
delay, the control board will re-energize the halted
compressor. If a low-pressure switch opens three times
within one hour of operation, the
Simplicity
™ control
board will lock-out the associated compressor and flash
an error code (See Table 10).
• An ambient air switch will lock out mechanical cooling at
40
F. If the product was equipped from the factory with
the low ambient option the unit will operate down to 0
F. If
the unit was not ordered with the factory low ambient
option a field installed low ambient kit is available.
The refrigerant systems are independently monitored and
controlled. On any fault, only the associated system will be
affected by any safety/preventive action. The other refrigerant
system will continue to operate unless it is affected by the fault
as well.
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.
When energized, the indoor blower has a minimum run time of
30 seconds. Additionally, the indoor blower has a delay of 10
seconds between operations.
Cooling Sequence Of Operation
Single-Stage Condenser Unit (J07YC)
A single stage cooling thermostat is required to operate the
condenser unit.
When the thermostat calls for cooling (Y1), the Simplicity
control board (UCB) closes the coils of relay RY1 and
contactors M1 and M3.
• Relay RY1 controls the crankcase heater (CCH1). The
normally closed contacts allow CCH1 to operate during
unit shutdown.
• Contactor M1 controls compressor COMPR1.
• Contactor M3 controls outdoor fans ODFAN1 & 2.
After completing the specified time for fan on-delay, UCB closes
the coil of relay BR1.
