Carrier AIRSTREAM 42WKN Installation, Operation And Maintenance Instructions Download Page 7

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CONTROLS DESCRIPTION

Microprocessor Control Board —

The PCB (print-

ed circuit board) control board (see Fig. 4) relays control the
operation of the indoor-fan motor, outdoor-fan motor, compres-
sor 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
• T3 Indoor Coil Temperature Sensor: 50K at 77 F

Outputs

INDOOR FAN MOTOR — The controller will switch a
combination of three, 10 amp, 230-vac (3 speed settings) resis-
tive rated relays to deliver the selected indoor fan speed.
CONDENSATE PUMP — The condensate pump will acti-
vate 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 re-
lay 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. 5-13 for typical 42WKN unit wiring diagram.

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
plastic bag and is placed inside the small rectangular box con-
taining the infrared transmitter. The battery should be installed
into the PCB's battery holder (see Fig. 4) approximately 5 min-
utes before main power 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 or optional pendant.

A microprocessor mounted in a metal control box enclosure

is used to control the entire unit operating functions with
adjustments 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. 14 for controller button and icon information.

Optional Pendant —

The optional pendant (see Fig. 15)

is a hard-wired replacement for the hand-held transmitter; it
has all the functionality of the transmitter but is field-mounted
and therefore cannot be misplaced.

The pendant assembly consists of the following parts:

• Pendant controller
• Pendant wall mounting bracket

Infrared Receiver —

The IR receiver (see Fig. 16) 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 (see Fig. 4).
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 determined. 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 sen-

sor failure.

Receiver Indicators —

See Fig. 17 for explanation of

receiver indicators.
NOTE: When the microprocessor is used in a master/slave net-
work AND is configured for slave operation, both the cool and
heat indicators will be lit, even during periods when the unit is
switched off.

Fig. 4 — Microprocessor Control Board

FL HP

COMP
OUT

HEAT
OUT

HEAT
IN

Compressor

Out

Compressor

Heat

Output

230VAC

Heater
Supply