Microprocessor Control - York YACT038-072 Installation Manual

Microprocessor Control

Startup
The unit will not operate until all the inputs and safety
controls are checked for normal conditions. At first power-
up, a four minute delay is employed before the compressor
is energized.
Component Sequencing Delays
Components are sequenced and delayed for optimum space
conditioning performance.
Accessory Relay
The accessory relay will be used to control a refrigerant
solenoid valve. The accessory relay will turn on when the
control is operating in forced air heating, forced air cooling
and when there is no active thermostat input. The relay will
be off when operating in hot water mode.
Loop Pump Linking Signals
A signal between multiple control boards at the inputs and
outputs (SL1-In and Out) will provide for remote control of
the loop pump on any unit.
Condensate Overflow Protection
The control board incorporates an impedance sensing
liquid sensor at the top of the drain pan. Upon a continuous
30-second sensing of the condensate, compressor operation
is suspended (see Fault Retry), and the condensate overflow
lockout LED begins flashing.
Shutdown Mode
A 24VAC Common signal to the "shutdown" input on the
control board puts the unit into shutdown mode. Compressor,
hot water pump, and blower operation are suspended.
Short Cycle Protection
The control employs a minimum "off" time of four minutes
and a minimum "on" time of two minutes for short cycle
protection of the compressor.
Safety Controls
The control receives separate signals for a high pressure
switch for safety, a low pressure switch to prevent loss of
charge damage, and a low suction temperature thermistor
for freeze detection limit. Upon a continuous 30-second
measurement of the fault (immediate for high pressure),
compressor operation is suspended, the appropriate lockout
LED begins flashing. (Refer to the "Fault Retry" section.)
AFFINITY COMBINATION INSTALLATION MANUAL
Testing
The control allows service personnel to shorten most timing
delays for faster diagnostics (Refer to Dip Switch description).
Fault Retry
All faults (except for low RPM faults with the ECM blower
motor) are retried twice before finally locking the unit out.
An output signal is made available for a fault LED at the
thermostat. The "fault retry" feature is designed to prevent
nuisance service calls.
Diagnostics
The control board allows all inputs and outputs to be
displayed on the LEDs for fast and simple control board
diagnosis. (Refer to Dip Switch description).
Resistance Heat Control (208-230 Units)
The electric heat control module contains the appropriate
high-voltage control relays. Control signals energize the
relays in the proper sequence, and the LED display board
indicates which stages are energized.
IntelliStart
Some models shall be equipped with an optional IntelliStart.
IntelliStart is a single-phase soft starter which reduces the
normal start current (LRA) by 60%. This allows the heat
pump to more easily go "off-grid." Using IntelliStart will also
provide a substantial reduction in light flicker, reduce startup
noise, and improve the compressor's start behavior. The
IntelliStart is self-callibrating and may take several starts to
optimize the compressor start behavior.
Features:
• Automatic adjustment of the compressor starting
current to the available supply voltage —maintaining
constant starting torque and current.
• Supply line impedance monitoring and compensation.
• Automatic compensation for residual backpressure in
the system.
• Monitoring of supply voltage while compressor is
running to prevent motor stalling, causing excessive
currents, under low voltage conditions.
• Light flicker reductions of up to 10:1 over LRA under
the same conditions.
ECM Airflow Selection DIP Switches (SW1)
A 12-position DIP switch package on the control allows the
airflow levels to be set for low, medium and high speed
when using the variable speed ECM blower motor (see
Blower Performance table).
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