Operation
Unit Control Overview
This series of heat pumps 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
The Simplicity™ control board monitors the following inputs for each cooling system:
•A
•A
•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.
Compressor Protection
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
The ASCD is initiated on unit
Flash Codes
The UCB will initiate a flash code associated with errors within the system. Refer to UNIT CONTROL BOARD FLASH CODES Table 11.
Reset
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.
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 Heat Pump (PC090)
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
When the thermostat calls for cooling (Y1), the Simplicity control board (UCB) closes the coils of relay RY1 and contactor
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