Controls Description; Microprocessor Control Board; Inputs; Outputs - Carrier AirStream 42WKN08-36 Installation, Operation And Maintenance Instructions

CONTROLS DESCRIPTION

Microprocessor Control Board

The PCB (printed circuit board) control board relays control the
operation of the indoor-fan motor, outdoor-fan motor, compressor
and electric heater (if fitted), to maintain room conditions at a
user-defined set point. Temperature settings, fan speeds and other
control functions can be changed by the infrared (IR) transmitter
or optional pendant. The controller PCB provides the following
input/output facilities:

Inputs

• T1 Return Air Temperature Sensor: 50K at 77°F (25°C)
• T3 Indoor Coil Temperature Sensor: 50K at 77°F (25°C)

Outputs

INDOOR FAN MOTOR

The controller will switch a combination of three 10 amp, 230-vac
(3 speed settings) resistive rated relays to deliver the selected
indoor fan speed.

CONDENSATE PUMP

The condensate pump will activate when unit is in cooling mode.

VANE MOTOR

A 10 amp, 230-vac resistive rated relay switches the vane motor
on when Air Sweep is selected (unit sizes 18-36 only).

ELECTRIC HEAT

A 30 amp, 230-vac resistive rated relay switches the electric heater
on when required.

External Connections

• Power input - Nominal 230-vac, 50/60 Hz
• Network connection - Twisted pair shielded cable
Refer to Fig. 5-34 for typical 42WKN unit wiring diagrams.

Microprocessor PCB Battery (P/N CR2032)

The microprocessor PCB is fitted with a battery backup system
that maintains the CPU (central processing unit) memory and
time clock settings during brief power outages. The battery is
small, round and silver in appearance, similar to a wrist watch
battery. When the unit is shipped, the battery is packed in a plas-
tic bag and is placed inside the small rectangular box containing
the infrared transmitter. The battery should be installed into the
PCB's battery holder approximately 5 minutes before main pow-
er is initially applied to the unit.

Controller

Before using the infrared transmitters, please read this handbook
fully and ensure the batteries (supplied loose) are fitted into the
IR transmitter.
A microprocessor mounted in a metal control box enclosure is
used to control the entire unit operating functions with adjust-
ments and settings being made from a hand-held IR transmitter or
optional pendant.
The controls include the following basic components:
• PCB control board
• Infrared transmitter or optional pendant
• Infrared receiver (fascia)
See Fig. 35 on page 41 for controller button and icon information.

Infrared Receiver

The IR receiver (see Fig. 36 on page 41) is an extension of the
control board and is located on the fascia of the unit, connected by
a 7-pin plug and socket.
The green on/off indicator will be illuminated when the unit is
running.
Yellow indicators show the present unit status, either "cool" or
"heat."
When both yellow indicators flash, the PCB control board battery
needs to be changed.
NOTE: Be careful not to damage the holder when changing the
battery.

Self Diagnostics

The microprocessor controller has a built-in diagnostics feature so
that in the event of an alarm, the nature of the fault can be deter-
mined. The red timer/alarm LED (light-emitting diode) flashes on
the fascia in a pre-determined frequency depending on the fault as
identified below:
1. Alarm LED flashes once every second: indoor coil sensor
failure, low coil temperature or condensate high level trip.
2. Alarm LED flashes once every 5 seconds: return air sensor
failure.

Receiver Indicators

See Fig. 36 on page 41 and "Operation" on page 55 for an expla-
nation of receiver indicators.
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