Whirlpool WMB Installation Instructions Manual Download Page 10

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SEQUENCE OF OPERATION

Cooling (cooling only or heat pump)

When the thermostat calls for cooling, the circuit between R and
G is completed, and the blower relay is energized. The Normally
Open contacts close, causing the indoor blower motor to
operate. The circuit between R and Y is also completed; this
circuit closes the contactor in the outdoor unit starting the
compressor and outdoor fan motor. Circuit R and O energizes
the reversing valve, switching it to the cooling position. (The
reversing valve remains energized as long as selector switch is
in the COOL position.)

Heating (electric heat only)

When the thermostat calls for heat, the circuit between R and W
is completed, and the heat sequencer relay is energized. A time
delay follows before the heating elements and the indoor blower
motor come on. Units with a second heat sequencer relay can be
connected with the first sequencer to W on the thermostat
subbase or connected to a second stage on the subbase.

Heating (heat pump)

When the thermostat calls for heat, the circuits between R and Y
and R and G are completed. Circuit R-Y energizes the contactor
starting the outdoor fan motor and the compressor. Circuit R
and G energizes the blower relay starting the indoor blower
motor.

If the room temperature should continue to fall, the circuit
between R and W 1 is completed by the second stage heat room
thermostat. Circuit R-W 1 energizes a heat sequencer relay. The
completed circuit will energize supplemental electric heat (if
available). Units with a second heat sequencer relay can be
connected with the first sequencer to W 1 on the thermostat or
connected to a second heating stage W 2 on the thermostat
subbase.

Variable Speed Features

Some WMB air handlers are equipped with a variable speed
motor and will deliver a constant airflow within a wide range of
external static pressures. The variable speed blower offers the
following comfort features:

Start

When called into operation, the variable speed motor will slowly
ramp up to normal operating speed. This eliminates the noise
and discomfort that results caused by the initial blast of air
encountered with standard air handlers. It can take up to
7.5 minutes to reach normal operating speed.

Continuous Blower Operation

The comfort level of the living space can be enhanced when
using this feature by allowing continuous circulation of air in
between calls for cooling or heating. The circulation of air
between calls for cooling or heating occurs at 50% of the
normal airflow rate (350 CFM minimum).

Reduced Airflow Operation

For situations where humidity control is a problem, the variable
speed motor can be enabled to operate at a 10% reduction in
the normal airflow rate under the control of a humidistat. This
can be achieved by connecting to a standard humidity control
that is normally closed and opens on humidity rise.

The Control Board

The control board regulates airflow selection and features LED
indicators that display operating mode, humidity control, and
airflow CFM. The red LED flashes once for each 100 CFM. For
example, if the operating CFM is 1200, the CFM LED will flash
12 times, then pause before repeating the 12-flash pattern.

Thermostat signals for emergency heat (EM), optional auxiliary
heat (W1), reversing valve (O), compressor (Y1), and blower (G)
are all indicated by lit LED’s on this board.

This model is designed for use with heat pumps as well as air
conditioning systems. The control board needs to sense a signal
on the “O” thermostat wire in order to use cooling delay timing.
For a straight air conditioning system, connect the “O” wire to the
thermostat “R” wire.

AIR HANDLER MAINTENANCE

IMPORTANT: Do not operate system without a filter. A filter is
required to protect the coil, blower, and internal parts from
excessive dirt and dust. See “Installation Configurations” for the
location of the filter in the unit cabinet and the service panel
giving access to unit filter. The filter is placed in the supply air
return duct by the installer.

■

Inspect air filters at least once a month and replace or clean
as required. Dirty filters are the most common cause of
inadequate heating or cooling performance.

■

Replace disposable filters. Cleanable filters can be cleaned
by soaking in mild detergent and rinsing with cold water.

■

Install new/clean filters with the arrows on the side pointing in
the direction of airflow.

■

Do not replace a cleanable (high velocity) filter with a
disposable (low velocity) filter unless return air system is
properly sized for it.

■

If water should start coming from the secondary drain line, a
problem exists which should be investigated and corrected.
Contact a qualified person.

ASSISTANCE OR SERVICE

If you need further assistance, you can write to the below
address with any questions or concerns:

Whirlpool

Home Cooling and Heating