Indoor Unit Circuit Board - Haier 2U18MS2VHB Service Manual

6 Piping Temperature Sensor
The Piping Temperature Sensor senses indoor coil temperature in the cooling mode and in the heating mode. This sensor is
used for Anti Freezing and Anti Cold Blow cycles. The sensor also provides critical temperature information to the ECU that
may be used in frequency adjustments.
7 Condensate Pump
The Medium Static Ducted unit has a built in condensate pump. The pump is connected to the circuit board. The pump
is energized whenever the Float Switch indicates that water needs to be pumped from the cassette. The float switch
connects onto the circuit board.
The float switch and pump are located behind the removable insulated cover next to the electrical control box. The pump
is hermetically sealed and requires no maintenance. The float switch is a normally closed switch, that opens as water rises.
The float switch requires no maintenance.
Gravity Drain Ports
8
The indoor unit has the option for either gravity drain systems or the use of an internal condensate pump with float switch.
The pump is capable of minimal lift. If high lift is required, the water from the Medium Static Ducted unit should be pumped
to a field supplied condensate pump that is capable of high lift.

Indoor Unit Circuit Board

The indoor unit circuit board controls the switching functions of the indoor unit. All control decisions are made by the outdoor
unit ECU. The indoor board has some limited diagnostic capability which will be covered in this manual.
1 CN13 Float switch
2 CN22 Wired controller
3 CN41 Ambient and Coil sensors
4
CN4 Condensate pump
5
CN6 Blower motor
6
Terminal Block
MEDIUM STATIC DUCTED (PRO SERIES) TECHNICAL OVERVIEW
Components
1
2
3
5
4
6
H3