Friedrich Floating Air Pro Multi-Zone FPHMR42A3A Service Manual page 192

Control Logic Description
Heating Mode
Indoor fan:
The fan of the indoor unit will not run until the heat exchanger of the indoor unit reaches
a high enough temperature. This prevents cold air blowing into the space. After the indoor
coil reaches adequate temperature, the speed can be selected as high, medium, low, or auto.
Auto fan:
T1 is indoor room temperature. Ts is setting temperature.
Outdoor fan:
Once the outdoor fan starts up, it will operate as follows:
Single outdoor fan: The fan will start with irregular speeds for about 10 seconds, then will
be throttled depending on outdoor coil and ambient air temperature.
Double outdoor fan: The upper and lower fan start with irregular speeds for about 10
seconds, then will throttled depending on outdoor coil and ambient air temperature.
The lower fan will be 30rpm-60rpm less than the upper fan.
192
OPERATION
High
Medium
Low
0
2 Ts-T1
4