Johnson Controls PC090 THRU 240 Manuale Utente

430645-YIM-D-0610

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Johnson Controls Unitary Products

This series of heat pumps come factory equipped with 
Simplicity™ controls to monitor all unit functionality and 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. 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 11).

• 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 11).

• 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.

In addition to the external pressure switches, the compressors 
also have inherent (internal) protection. If there is an abnormal 
temperature rise in a compressor, the protector will open to shut 
down the compressor. The UCB incorporates features to 
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 any time a compressor is energized.

The ASCD is initiated on unit start-up and on any compressor 
reset or lock-out.

The UCB will initiate a flash code associated with errors within 
the system. Refer to UNIT CONTROL BOARD FLASH CODES 
Table 11.

Remove the call for cooling, by raising thermostat setting higher 
than the conditioned space temperature. This resets any 
pressure or freezestat flash codes. Simplicity™ only has 
minimum run time in cool. Heat pump mode shuts off 
immediately.

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.

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.

A single stage thermostat is required to operate the heat pump 
in cooling mode.

The reversing valve is energized during cooling mode.  A 
continuous 24V signal is passed through the normally closed 
contacts of relay RY2 to the "O" terminal of the Defrost Control 
Board (DC).  The normally closed relay DR-2 within DC 
energizes the solenoid (SOL) of the reversing valve.

When the thermostat calls for cooling (Y1), the Simplicity 
control board (UCB) closes the coils of relay RY1 and contactor