8
. TROUBLESHOOTING
8
-1. Overview
(1) Before engaging in troubleshooting
(a) Applicable models
All Super Modular Multi System (SMMS-
) models.
(Indoor units: MM
-UP
, Outdoor units: MMY-M
P
)
(b) Tools and measuring devices required
• Screwdrivers (Philips, flat head), spanners, long-nose pliers, nipper, pin to push reset switch, etc.
• Multimeter, thermometer, pressure gauge, etc.
(c) Things to check prior to troubleshooting (behaviors listed below are normal)
CAUTION
The cooling performance may be declining considerably when total operating capacity of cooling indoor units
is less than 4 HP while ambient temperature is below.
(2) Troubleshooting procedure
When a problem occurs, proceed with troubleshooting in accordance with the procedure shown below.
NOTE
Rather than a product trouble (see the List of Check Codes below), the problem could have been caused by
a microprocessor malfunction attributable to a poor quality of the power source or an external noise. Check
for possible noise sources, and shield the remote controller wiring and signal wires as necessary.
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1
A compressor would not start
• The air conditioner is being controlled by the 3-minute protective function.
• It is in standby status though the room temperature has reached the setup
temperature.
• It is being operated in timer mode or fan mode.
• It is being in initial communication.
2
An indoor fan would not start
• The air conditioner is being controlled by the cool air discharge preventive
function in "heating"?
3
An outdoor fan would not start or would
change speed for no reason
• The air conditioner is being operated in "cooling" under the low outside air
temperature.
• It is being operated in defrost operation.
4
An indoor fan would not stop
• The air conditioner is being controlled by function of residual heat
elimination being performed as part of the air conditioner shutdown
process after heating operation.
5
The air conditioner would not respond to a
start/stop command from a remote controller
• The air conditioner is being operated under external or remote controller.
Problem
Any other
problem
Investigate check code
displayed on interface P.C. board
of header unit
Investigate check code
displayed on interface P.C.
board of relevant follower unit
Check
the problem
site or
problem
part
"E28"
check code
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