Service manual

Operation Section

(2) Relay board

• The relay board receives signals and outputs

from the control board that contains a

microprocessor. The relay board contains the

compressor, fan on and fan mode (speed)

relays.

• It also contains a step-down transformer that

converts the line voltage (208/230 VAC) to

12 V.

• This 12 V is then converted from AC to DC and

used for relay coil activation. The 12 V (DC) power is sent to the control panel assembly where

it is further reduced to 5 V for the system logic.

• The relay board also contains the DIP switch.

• The DIP switch is used to change the fan mode operation from stop to operate and change both

the set point and room temperature display from Fahrenheit to Celsius.

< NOTE >

The relay board must be serviced as a complete assembly. It has only one serviceable

component, the fuse. (see below)

(3) Relay board fuse

• This fuse provides protection against damage

to the step-down transformer. It must be

replaced with the exact type of fuse or an

equivalent.

Specifications:

- 0.25 A, 250 V

CAUTION

Failure to use the exact type of fuse could result in damage to the unit and/or to components. It

could also void the warranty of the unit.

I002196

Dip Switch

Fan Mode Control

Switch

(STOP

⇔

OPERATE)

Temperature Scale

Display Switch

(°C

⇔

°F)

I002197

Fuse