Seabreeze PTAC09CH3ZX, Service Manual

Page: 2 / 15

953-0002-revC 07/06/09
PAGE 2
1. Function of the Control Board (PC board)
1.1 Cooling
●
The indoor temperature is monitored by the room temperature sensor. The temperature is
controlled by the cyclic switch of the compressor under which is controlled by the Control
Board.
●
Compressor startup is determined when the room temperature is more than or equal to
Ts+3.6
℉
(Ts is the setpoint temperature). When this occurs, the compressor, condenser fan,
and inside blower fan starts.
●
When the setpoint is satisfied as determined by the temperature sensor, the compressor,
condenser fan, and the blower fan will stop. This cycle will start again when the
temperature rises as notes before.
a. Working curve for temperature control
1.2 Freeze protection and frost protection function of unit
●
When the outdoor coil temperature is less than or equal to 57 ºF, the compressor will not
run. The blower will continue to run at its set speed.
●
After the compressor runs continuous for over 3 minutes and if coil pipe temperature of
inside is continuously ≤ 5ºF for over 3 minutes, then the compressor will shut off. The blower
fan will continue to run. The system will restart after 6 minutes. If the system goes into this
condition again, the unit will shut down and display error code of E8.(See Error Code
Chart)
1.3Heating
●
The indoor temperature is monitored by the room temperature sensor. The temperature is
controlled by the cyclic switch of the compressor under which is controlled by the Control
Board.
●
Normally, in heating mode, the compressor and the outside blower fan will start. The Four-