Manual 2100-538A
Page
17 of 23
Indoor Blower Operation
The indoor blower speed will modulate with the
compressor operation from 50% to 100% of operation.
Once compressor operation is at 50 or below, percent
airflow will be at 50% and no further reduction of
airflow will occur. Modulation is accomplished by
modulating a 0-10 volt signal from OUT 7 to the indoor
blower control board which then sends a PWM signal to
the indoor blower motor.
An additional option to maintain airflow at 100% is also
available.
Outdoor Fan Motor Operation
The outdoor fan motor speed is varied in response to
outdoor air temperature and pressure. The fan motor
will cycle on and off with the compressor when not in a
Test Mode. At all times above 115 degrees OAT, the
outdoor fan, OUT 9, will be energized at high speed.
From 115 degrees to 55 degrees the outdoor fan, OUT
9, will be set at normal outdoor airflow. Below 55
degrees the outdoor fan will modulate to maintain a 300
psi head pressure. This will act as a low ambient fan
cycling control. The output may go to zero output to
maintain the 300 PSI. The outdoor ECM motor will be
programmed with a minimum RPM allowed to protect
the bearing system. Any signal that is less than the
percent torque required to maintain the minimum RPM
will cause the motor to shut off. Once head pressure
rises the motor will restart.
High head pressure operation mode
- When the unit
head pressure exceeds 615 PSI, the Unit will modulate
pressure down until it is at or below 575 psi. Controls
will indicate head pressure control mode on the display
when this occurs.
HEATING SEQUENCE
On a call for heating, if the space temperature falls 1°F
below setpoint, the first stage of heating, RLY 4, will
cycle ON. If the space temperature falls 3°F below
setpoint, the second stage of heating, RLY 5, will cycle
ON. Indoor Blower airflow is maintained at the Rated
unit airflow at all times during heating.
