Lennox MS8 SERIES User manual

This manual is the property of the homeowner
and must be left with the user.
2012 Lennox Industries Inc.
Dallas, Texas, USA
MS8
Single-Zone
Mini-Split System
Air Conditioners
and Heat Pumps
507022-01
10/2012

2
Warnings
WARNING
ELECTRICAL SHOCK, FIRE, OR EXPLOSION HAZARD.
Failure to follow safety warnings exactly could result in dangerous op
eration, serious injury, death or property damage.
Improper installation, adjustment, alteration, service or maintenance
can cause property damage, personal injury or loss of life. Installation
and service must be performed by a licensed professional installer (or
equivalent), or a service agency.
Any additions, changes, or conversions required in order for the ap
pliance to satisfactorily meet the application needs must be made by a
licensed professional installer (or equivalent) using factory-specified
parts.
If you do not follow these instructions exactly, a fire or explosion may
result causing property damage, personal injury or death.
For your safety and to fulfill the terms of the limited warranty, a licensed
professional service technician (or equivalent) must annually inspect
this system.
This unit must be properly grounded.
Do not use this system if any part has been underwater. A flood-dam
aged appliance is extremely dangerous. Immediately call a licensed
professional service technician (or equivalent) to inspect the system
and to replace all controls and electrical parts that have been wet or to
replace the system, if deemed necessary.
Keep combustible materials at least 3 feet away from either the indoor
or outdoor unit.
Do not insert your hands, tools or any other item into the air intake or
air outlet at either the indoor or outdoor unit.
If outdoor unit is installed on a raised stand, check condition of stand
occasionally to ensure that it remains stable.
DO NOT spray water on the indoor unit for any reason.
Do NOT install sprinkers or soaker hoses where they can expose the
outdoor unit to treated water. Prolonged exposure to treated water will
corrode the surface of the steel and aluminum parts and will diminish
the performance of the unit.

3
Parts Arrangement
Indoor unit
Outdoor unit
Wall Pipe
Drainage hose
Air in
Air out
Wrapping Tape
epipnoitcennoC
Air inlet
(Typical indoor unit shown. Actual unit may be slightly different.)
Front Panel Display
Air outlet
Filter
Directional Louver
Wireless remote control
Temperature
Heating
Indoor Unit Display
Cooling Power/Run
Dehumidification
Receiver
Setting
(or error code)

4
Important Operating Instructions
IMPORTANT
To ensure comfort, make sure that temperature selection has been
properly set at the remote control.
To ensure efficient operation, do not block air intake or outlet at either
the indoor or outdoor unit.
Do not stand on outdoor unit or store items on top of unit.
Make sure that indoor unit directional louver is properly adjusted.
System Operation
Cooling Operation
In the cooling mode, the indoor coil absorbs the
heat from the room and transfers it to the outdoor
coil where it is discharged. The system cooling
capacity is affected by the outdoor ambient tem
perature. The indoor fan operates continuously in
the COOL mode. The indoor unit directional lou
ver is fixed in an upward position.
In 115V systems, when the outdoor ambient tem
perature falls below 32°F (0°C), the indoor unit
control locks out operation to protect the system.
The cooling mode operating range of the outdoor
unit in these systems is typically from 41°F (5°C)
to 115°F (46°C).
In 208/230V systems, the cooling mode operating
range of the outdoor unit is typically from 23°F
(-5°C) to 118°F (48°C).
Heating Operation
The refrigerant flow is reversed during the heating
cycle. In this case, the outdoor coil absorbs the
heat from outside and transfers it to the indoor coil
where it is discharged into the room. The system
heating capacity is also limited by the available
heat in the outdoor ambient air.
In the HEAT mode, the indoor fan will remain OFF
for two minutes in the following instances:
 at the beginning of each heating cycle,
 after a defrost cycle has ended,
In the heating mode, the indoor blower will contin
ue to operate for 60 seconds after the outdoor unit
has shut off. The indoor unit directional louver is
fixed in a downward position.
In climates with very low winter temperatures, it
may be necessary to supplement heating by addi
tional means (space heater, fireplace, etc.).
In heating mode, the operating range of the out
door unit is typically from 05°F (-15°C) to 86°F
(30°C).
AUTO Mode Operation
When the system is set to operate in AUTO mode,
the indoor and outdoor units work together to
meet a series of preset demands. The remote
control temperature setpoint and fan operation
functions are not adjustable in the AUTO mode.
In AUTO mode, if the indoor ambient temperature
is greater than 77°F (25°C), the unit will operate
in the cooling mode. The outdoor unit will run until
the indoor ambient temperature reaches 75°F
(24°C). At this point, the outdoor unit compressor
and outdoor fan will operate for another 60 sec
onds, then they will both turn off. The indoor fan
will run continuously at a speed determined by the
indoor ambient temperature. During AUTO cool
ing operation, the indoor unit directional louver is
fixed in an upward position.
Heat Pump Systems Only -- In AUTO mode, if the
indoor ambient temperature is less than 68°F
(20°C), the unit will run in heating mode. The out
door unit will run until the indoor ambient temper
ature reaches 69°F (21°C). At this point, the out
door unit compressor and fan will operate for
another 60 seconds, then they will both turn off.
The indoor fan will run continuously at a speed
determined by the indoor ambient temperature.
During AUTO heating operation, the indoor unit
directional louver is fixed in a downward position.
FAN Mode Operation
When the system is set to operate in FAN mode,
the indoor fan runs continuously in AUTO, low,
medium or high speed. The outdoor unit is off. In
AUTO fan mode, the fan speed is determined by
the indoor ambient air temperature.
DEHUMIDIFICATION Mode Operation
When the system is set to operate in DEHUMID
IFICATION mode, the indoor fan runs continu
ously in low speed.

5
Wireless Remote Functions
The wireless remote control provides system control to the homeowner at the touch of a
button. The indoor unit and remote control send information back and forth continuously.
The remote control must be placed on a table or other surface in direct line of sight with
the indoor unit infrared receiver. The remote control should not be placed in a drawer.
Make sure that there are no obstructions between the indoor unit receiver and the remote
control. Do not drop the control or spill liquid on the remote control.
POWER button
Press this button once to turn
system on. Press again to
turn the system off. When the
POWER button is used to turn
the system OFF, it overrides the
Sleep Timer function (when it is
in use).
MODE button
Press this button to select system
operating modes. AUTO mode is
the default setting. Press MODE
button again to select COOL mode,
again for DEHUMIDIFICATION
mode, again for FAN mode and
again for HEAT mode (heat pumps
only).
Selected mode is displayed on both
remote and indoor unit cover panel.
+/- buttons
Use plus (+) and minus (-) but
tons to adjust the temperature
setting up and down.
NOTE - The temperature cannot
be adjusted when the system is
in AUTO mode.
Press - and + buttons simulta
neously to either lock or unlock
the remote control buttons.
When the remote control is
locked, the icon is
displayed.
AUTO
COOL
DEHUMIDIFICATION
FAN
HEAT
FAN button
Press this button to select fan
speed. AUTO fan is the default
setting. In AUTO fan mode, the
indoor fan speed is determined
by the indoor ambient tempera
ture. Press FAN button to step
through FAN setting selections:
AUTO, low speed, medium
speed and high speed.
Selected fan speed is shown at
the top of the remote control dis
play.
NOTE - The fan speed is not
adjustable during DEHUMIDIFI
CATION mode operation. The
low fan speed is necessary
to ensure optimal humidity
control.
AUTO
Low Medium High
UNUSED buttons
These buttons are not
functional in the MS8
system.
I FEEL button
Press the I FEEL button to acti
vate the I FEEL feature. When
the I FEEL icon appears,
temperature sensor in remote
control (rather than return air
sensor in indoor unit) is used to
initiate heating or cooling de
mands. Press I FEEL button
again to cancel I FEEL feature
and transfer room temperature
sensing back to return air sensor
in indoor unit.
IMPORTANT - In I FEEL mode,
remote control must be placed
on a table or other surface in
direct line of sight with the in
door unit infrared receiver.
The control should not be
placed in a drawer. Make sure
that there are no obstructions
between the indoor unit re
ceiver and the remote control.
Ensure proper operation of
unit before permanent installa
tion of optional wall mounting
bracket.

6
Wireless Remote Functions (Continued)
TURBO button
Use the TURBO button to
initiate or cancel high-speed fan
operation to accelerate cooling
or heating of the ambient room
temperature. The turbo icon
is displayed when the function is
turned on.
CLOCK button
Use the CLOCK button to adjust
the time displayed on the remote
control. Press the CLOCK button
once. The clock icon will
flash. Within 2 seconds, use the
- and + buttons to adjust the time
down or up in one-minute incre
ments. Press the button continu
ously to adjust the time in
10-minute increments. Press the
CLOCK button again when cor
rect time is displayed.
BLOW button
Use the BLOW button to
extend low speed blower
operation for 10 minutes
at the end of a cooling
demand.
The extended fan (BLOW)
operation ensures that excess
moisture is removed from the
indoor coil before the blower
shuts off.
Press the BLOW button once to
initiate extended blower opera
tion. Fan operation ends after 10
minutes.
The extended fan (BLOW)
operation icon is displayed
when the feature is turned on.
Extended fan (BLOW) operation
is available in cooling or dehu
midification modes; extended fan
(BLOW) operation is not avail
able in AUTO, heating or fan
mode.
SWITCH FROM °C TO °F
With system OFF, press MODE
and - buttons simultaneously to
switch from Centigrade to
Fahrenheit. Current selection
is displayed to the right of the
temperature display.
SLEEP button
Use the SLEEP button to initiate
or cancel the sleep function.
Press SLEEP button. When
sleep icon appears, press
TIMER OFF button and use -
and + buttons to set time for sys
tem shutdown. When desired
time is displayed, press TIMER
OFF button again. Press SLEEP
button to cancel sleep function.
In cooling mode, SLEEP function
increases temperature (+1.8°F
per hour) over a two-hour period
after the selected sleep time.
In heating mode, SLEEP function
decreases temperature (-1.8°F
per hour) over a two-hour period
after the selected sleep time.
NOTE - The sleep function is not
available in AUTO or FAN
modes.
TIMER ON button
Use the TIMER ON button to ini
tiate or cancel a single timed-on
event. Use this feature to bring
the system on just before you re
turn home or just before you
wake in the morning.
Press the TIMER ON button
once. The clock icon
disappears and a time setting
appears with the word ON flash
ing at the right. Use the - and +
keys to adjust the time setting to
the desired time for the system
to begin operation. Press the
TIMER ON button again to
accept the setting. When suc
cessfully set, the word ON will
appear to the right of the current
time display. Press the TIMER
ON button again if you want to
cancel the timed-on event.
TIMER OFF button
Use the TIMER OFF button to
initiate or cancel a single timed-
off event. Use this feature to turn
the system off just after you
leave the house or just after you
go to bed at night.
Use the same method
described above to set the de
sired time for the system to stop
operation. When successfully
set, the word OFF will appear to
the right of the current time dis
play. Press the TIMER OFF but
ton again if you want to cancel
the timed-off event.
LIGHT button
Use the LIGHT button to turn the
indoor unit display light on and
off. When the light is on, the
icon appears on the remote con
trol.

7
Wireless Remote Functions (Continued)
Press the TEMP button again to
display the outdoor ambient tem
perature icon. The outdoor
ambient temperature display is
not available on this system.
On occasion, the remote control
will display the temperature that
was not selected (indoor ambient
temperature or setting tempera
ture). The selected temperature
will return to the display screen
after 5 seconds.
NOTE - The TEMP button can
also be used to temporarily dis
play the indoor ambient tempera
ture on the indoor unit display
panel.
LOUVER SETTING button
Use the LOUVER SETTING but
ton to choose a preferred louver
setting, rather than the default
setting, during fan operation.
Refer to the following section for
louver operation.
TEMP button
Use the TEMP button to change
the temperature display shown
on the remote control. When ini
tially powered on, the current
temperature setting is displayed,
along with the icon.
Press the TEMP button once
to alter the display to show the
current indoor ambient tempera
ture, along with the icon. The
indoor temperature sensor is in
the indoor unit.
Louver Operation
LOUVER SETTING button
Use the LOUVER SETTING
button to choose a preferred
setting for the indoor unit
directional louver.
NOTE - Actual louver
position is different than
what is shown on remote
icon. See comparison to
the right.
Press the LOUVER
SETTING button once to
activate the full-range
oscillation mode from top to
bottom, then back again. The
louver icon will appear in
the lower section of the
screen.
Press the LOUVER
SETTING button again to
turn the feature OFF. The
louver will return to the
default setting.
Press the LOUVER
SETTING button twice and
continue to press the button
to scroll through the five
available fixed positions
AND three other oscillating
positions.
o r a b o v e
REMOTE
CONTROL ICON
POSITION
ACTUAL
LOUVER
POSITION
To return the louver to the
default position, press the
LOUVER SETTING button
until the icon disappears.
Default Louver Positions
When the louver setting icon
is not displayed, the louver is
in the DEFAULT position.
When the remote control is
powered OFF, the default
position is fully closed.
When the remote control is
set so that the unit is in
COOLING, AUTO COOLING,
or DEHUMIDIFICATION
mode, the louver is in a fixed
upward position .
When the remote control is
set so that the unit is in HEAT
or AUTO HEATING mode and
the outdoor unit is OFF, the
louver is fixed in the second
position pointed upward. If
the outdoor unit is ON, the
louver is fixed in a downward
position .
When the remote is set for
continuous indoor fan to be
ON, the louver is fixed in an
upward position .
LOUVER
SETTING
ICON

8
System Start Up Using Wireless Remote
General Operation
1 - Press POWER button once to turn system on.
2 - Press MODE button until desired operating
mode icon is displayed.
NOTE - When AUTO mode is selected, the
temperature setting is not displayed on the
remote control. The - and + buttons cannot be
used to make temperature setting selections.
3 - Press - or + buttons until desired temperature
setting is displayed.
NOTE - Skip this step in AUTO mode.
4 - Press FAN button until desired fan speed icon
is displayed.
NOTE - Fan speed will be set to low if
DEHUMIDIFICATION mode has been selected.
5- Press LOUVER SETTING button to control
indoor unit directional louver. Press once to
activate full range oscillation. Press more than
once to scroll through and select one of five
fixed positions or one of three other oscillating
positions. If function is activated when unit
powers off, preferred setting will be activated
again when unit operation is restored.
Special Functions
6 - Press SLEEP button to initiate sleep function.
Then press TIMER OFF button to set timed
off.
7 - Use TIMER ON and TIMER OFF buttons to
schedule desired timed on and off settings.
8 - Use LIGHT button to set display light on or
off.
9 - Use BLOW button to turn on and off extended
fan operation feature.
10-Use TURBO button to turn accelerated fan
speed on or off.
11-Use I FEEL button to use temperature sensor
in remote control (rather than return air
sensor in indoor unit) to initiate cooling and
heating demands.
1
2
3
4
5
7
8
9
10
6
11

9
Remote Control — Important Information
The wireless remote control requires two AAA, 1.5V batteries.
DO NOT attempt to use any other type of battery.
Follow the steps below and in the illustrations to replace the
batteries when necessary.
1 - Remove screw that secures the battery access panel to
the remote. Place thumb on at the top of the battery
access panel on the back of the remote control. Slide
the panel in the direction of the arrow.
2 - Remove the existing AAA, 1.5V batteries.
3 - Replace batteries with fully charged AAA, 1.5V batteries.
NOTE - Pay attention to proper polarity of batteries. Remote
control will not operate if batteries are improperly installed.
4 - Reposition battery access panel and slide forward until
panel snaps into locked position. Reinsert screw.
Remote should remain within its receiving range to ensure proper system control.
Control should be kept at least 3 feet (914mm) away from other electrical appliances
(televisions, stereos, etc.) to prevent signal interference.
If remote control operation becomes erratic, remove batteries. Wait 30 seconds and
reinsert batteries. If proper remote operation is not restored, replace batteries.
SCREW
SCREW
IMPORTANT !
If wireless remote will not be used for a long period of
time, remove batteries to avoid damage to the control.
To verify that the remote control is transmitting com
mands to the indoor unit, press any command key and
a wireless icon will appear in the upper right-hand
corner of the remote control display.
When being used in the I FEEL mode, the remote con
trol must be placed on a table or other surface in direct
line of sight with the indoor unit infrared receiver. The
control should not be placed in a drawer. Make sure that
there are no obstructions between the indoor unit receiv
er and the remote control.

10
Maintenance
WARNING!
Turn off all power to unit at system disconnect switch (at the
outdoor unit) or circuit breaker before performing any main
tenance procedures! Failure to follow this warning could
lead to personal injury or death.
Coil fins are very sharp! Take care not to touch the fins in
order to avoid injury.
Indoor Unit Filters
The indoor unit filter should be cleaned every three months, or
more frequently, if necessary.
Follow the steps below and in the illustrations to clean the filters.
1 - Pivot indoor unit front panel out and up to access filters.
2 - Gently pull each filter outward, then down to remove the fil
ters from the unit
3 - Use a vacuum cleaner to remove dust and dirt from each fil
ter or wash the filters with warm water and a mild detergent.
Rinse filters thoroughly with clean water and set aside to air
dry.
CAUTION!
Do not use hot water to clean the filters. Exposure to wa
ter temperatures above 113°F (45°C) will damage filter
media and frame.
4 - Reinsert clean, dry filters and close unit front panel. Restore
power to unit.
1
2
3
4
Indoor Unit
Check to make sure that there are no objects on top of unit or around unit that may be obstructing air
flow. Check to make sure that indoor unit and wall bracket are secure and have not been damaged.
Use a clean, dry cloth to gently remove dust from the outer surface of the indoor unit. The cloth may
be slightly dampened with warm water, if necessary. Do not use soap or other cleaners.
CAUTION!
Hot water, soaps or other cleaning agents may damage indoor unit cabinet or display panel.
Do not use hot water (above 113°F [45°C]). Cloth must be damp only (NEVER WET) to avoid
damage to display. Do not use soap or other cleaning agents (window cleaner, abrasive
cleansers, etc.) to clean the indoor unit cabinet.
Outdoor Unit
Check to make sure that there are no objects on top of unit or around unit that may be obstructing air
flow. If the outdoor unit is installed on a wall bracket, make sure that bracket is secure and has not
been damaged. Use a clean, slightly dampened cloth to gently remove dust from the outer surface of
the outdoor unit. Do not use soap or other cleaners and DO NOT spray water into unit.
WARNING!
SHOCK HAZARD! DO NOT SPRAY water into outdoor unit. Failure to follow this warning could
lead to electrical shock, resulting in personal injury or death.
Lennox recommends annual inspection by a licensed professional service technician, or equiva
lent.

11
Troubleshooting
WARNING!
ELECTRICAL SHOCK HAZARD! Never attempt to repair the indoor or outdoor unit yourself. System repairs must be
performed by a licensed, professional technician, or equivalent.
If any of the following conditions exist, immediately turn the system (indoor and outdoor units) off at the unit disconnect
switch and call a licensed professional technician, or equivalent, for repairs
There is a very loud sound during unit operation.
There is a terrible odor coming from the indoor unit during operation.
Water is leaking into the room.
The circuit breaker trips frequently.
Water or some other liquid has been splashed into the indoor unit.
If none of the above conditions exist, check the following items before calling for repairs. This can save you both time
and money.
Problem Possible Cause
Unit does not operate immediately when restarted. Unit control initiates a 3-minute delay at the end of each cycle to protect
the compressor from damage.
A whoosh or gurgling noise can be heard at the indoor unit. Sometimes, the refrigerant can be heard in the indoor coil when the
outdoor unit starts or stops operation. This is not a malfunction.
Mist is coming out of the indoor unit during cooling operation.
This sometimes happens when the indoor temperature and humidity are
very high and the air is being cooled quickly. The mist will disappear as
the indoor temperature and humidity are lowered.
A creaking or popping noise can be heard when the unit starts or stops. The plastic components of the indoor units sometimes expand and con
tract when they are heated and cooled.
Unit is not operating.
Are the TIMER ON and TIMER OFF features being used incorrectly?
Is power disconnected or has circuit breaker tripped.
Is power shut down?
System is not cooling (or heating) efficiently.
Is temperature setting correct?
Are either the air inlet or air outlet blocked on the outdoor or indoor unit?
Is filter dirty?
Is fan at low speed?
Are windows and doors properly shut?
Wireless remote is not working.
Is remote in direct line of sight with indoor unit infrared receiver? Has
the remote been damaged?
Remove remote control batteries for 30 seconds, then reinsert them.
Replace batteries, if necessary.
Water is leaking from indoor unit. Indoor humidity level is very high and water is being blown from indoor
coil. This will stop as humidity level is reduced.
Water is leaking from condensate line at Water is leaking from conden
sate line at indoor unit.indoor unit.
Check condensate line outside to make sure it is not obstructed.
Check condensate line to make sure it has not been disconnected from
indoor unit.
Water is leaking from the outdoor unit.
During operation in high-humidity areas, condensate will form on cold
outdoor refrigerant pipes.
When heat pump is operating in defrost mode, ice will thaw from around
outdoor coil and water will flow from the unit.
Clicking noise heard inside.
Sometimes, the sound of the outdoor unit fan or compressor relay can
be transmitted in a way that makes it seem to be coming from the indoor
unit.
Indoor fan is not working.
Heat pump units -- In HEAT mode, a timed delay keeps indoor fan off
for two minutes to prevent unheated air from being circulated by the
indoor fan.
Heat pump units -- In HEAT mode, cold outdoor temperatures and high
humidity cause frost to accumulate on the outdoor unit. When this hap
pens, the unit will enter a defrost cycle. The indoor fan is off during the 3
- 12 minute cycle.
In DEHUMIDIFICATION mode, indoor fan operation may be stopped to
avoid delivery of moist air to the room. Do not adjust temperature set
ting.

12
Auto ON Switch
If the remote control is lost or damaged, or if
charged AAA, 1.5V batteries are not avail
able, the Auto ON switch can be used to turn
the system on or off.
The Auto ON switch is located behind the
cover panel on the indoor unit. Lift the front
panel and press the ON button once briefly to
start the system. To stop emergency opera
tion, push the ON button again.
IMPORTANT !
The Auto ON button initiates operation in
the AUTO mode. The temperature and fan
speed are not adjustable in the AUTO
mode.
AUTO
PENCIL OR OTHER
NON-METALLIC OBJECT
AUTO BUTTON
PRESS
WITH
FINGER
AUTO Switch
(Recessed)
AUTO Switch
(Not Recessed)
Error Codes
If a problem occurs with the system, an error code will replace the temperature setting displayed on
the front cover of the indoor unit. If more than one error has occurred, the codes will alternate so
that all codes are shown. Make note of the code (E4, F6, H4, etc.), then reset the display by pressing
the ON/OFF button on the wireless remote. Press the ON/OFF button a second time to reapply pow
er to system. If code is still displayed, disconnect and restore power at the unit disconnect switch
or circuit breaker. If the problem was temporary, the code will not reappear. If the error code re-ap
pears after power has been broken and restored at the disconnect switch or circuit breaker, call a
licensed professional service technician.
HEAT INDICATOR COOL INDICATOR
TEMPERATURE*
RUN
DEHUMIDIFY MODE
INFRARED
SIGNAL
RECEPTOR
* The temperature readout will be replaced
by an error code if there is a malfunction.
88