Table Of Contents; Control Box Component Identification; Operating Sequence - Mitsubishi Electric LAHN-1 Technical & Service Manual

Contents
1. Control box component identification .....................................2
2. Operating sequence ...............................................................2
3. Damper blade adjustment ......................................................5
4. Damper actuator manual override .........................................8
5. Parts list ..................................................................................9
6. Wiring diagram .....................................................................10

1. Control box component identification

LAHK-1 Control Box Component Identification

Operating Sequence

2. Operating sequence
Outdoor Unit in Cooling Mode
The LAHK-1 low ambient hood is designed to reduce
Outdoor unit in cooling mode
The LAHN-1/LAHN-3 low ambient hood is designed to reduce the the airflow through the outdoor units as the ambient
airflow through the outdoor units as the ambient temperature drops.
temperature drops. This maintains the head pressure
This maintains the head pressure at a level that will allow the system
at a level that will allow the system to perform at 100%
to perform at full capacity down to -10°F outdoor temperature.
o
capacity down to -10 F outdoor temperature.
A thermistor mounted on the side of the unit senses the outdoor
A thermistor mounted on the side of the unit senses
temperature. As the outdoor temperature drops, the resistance of
the outdoor temperature. As the outdoor temperature
the thermistor increases. The thermistor is connected to the specially
designed circuit board and the resistance value from the thermistor
drops, the resistance of the thermistor increases. The
is converted to a DC voltage output within the circuit board. This DC
thermistor is connected to the specially designed circuit
voltage output drives the damper actuator to a predetermined position
board and the resistance value from the thermistor is
based on the outdoor temperature.
converted to a DC voltage output within the circuit
The inverter driven fan motor will adjust the discharge pressure based
board. This DC voltage output drives the damper
on system capacity demand. The motor will speed up and force more
actuator to a predetermined position based on the
air through the damper if there is a higher system capacity demand,
outdoor temperature.
or slow down if system capacity demand decreases.
The inverter driven fan motor will adjust the discharge
Outdoor unit in heating mode
pressure based on system capacity demand. The
Heating mode requires the damper be in the fully open position to
motor will speed up and force more air through the
allow full airflow and maximum heating capacity.
damper if there is a higher system capacity demand, or
Heating mode automatically deactivates the kit through an interlock
slow down if system capacity demand decreases.
relay. The coil for this relay is tied into the reversing valve connection
Specifications are subject to change without notice.
2
Outdoor Unit in Heating Mode
Heating mode requires the damper be in the fully open
position to allow full airflow and maximum heating
capacity.
on the outdoor unit. When the unit switches to heating mode, the
reversing valve is energized. This in turn energizes the interlock relay. Heating mode automatically deactivates the kit through
When the relay is energized, the normally closed contact opens. By
an interlock relay. The coil for this relay is tied into the
opening this contact, the power to the transformer and control board is
reversing valve connection on the outdoor unit. When
interrupted, this allows the damper to spring to the full open position.
the unit switches to heating mode, the reversing valve
is energized. This in-turn energizes the interlock relay.
Outdoor unit in defrost mode
When the relay is energized, the normally closed
If the outdoor unit will be running in heating mode, a defrost period
contact opens. By opening this contact, the power to
is inevitable. During defrost the low ambient controls see this as the
unit operating in cooling mode. If the outdoor temperature is below
the transformer and control board is interrupted, this
40°F, the damper will close to a position equal to that required during
allows the damper to spring to the full open position.
the cooling cycle. Once the unit comes back out of defrost and into
heating mode, the damper will again spring wide open for full airflow.
Outdoor Unit in Defrost Mode
If the outdoor unit will be running in heating mode, a
Operation test
Outdoor unit must be in cooling mode. defrost period is inevitable. During defrost the low
All hoods and damper controls are tested at the factory before shipping.
ambient controls see this as the unit operating in
To perform an operational test once the installation is complete, follow
cooling mode. If the outdoor temperature is below 50 F,
the steps below. Please refer to the chart and table below for detailed
the damper will close to a position equal to that
control logic.
required during the cooling cycle. Once the unit comes
back out of defrost and into heating mode, the damper
Operation testing when the outdoor ambient is ABOVE 40°F
will again spring wide open for full airflow.
1. Turn on power to the outdoor unit.
Operation Test
Outdoor unit must be in cooling mode
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