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8. TROUBLESHOOTING
8-1. Overview
(1) Before engaging in troubleshooting
(a) Applicable models
Super Heat Recovery Multi system (SHRM-u) models.
(Indoor units: MM -UP
(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)
N
O
.
A compressor would not start
1
An indoor fan would not start
2
An outdoor fan would not start or would
3
change speed for no reason
An indoor fan would not stop
4
The air conditioner would not respond to a
5
start/stop command from a remote controller
CAUTION
The cooling performance may be declining considerably when total operating capacity of cooling indoor
units is less than 36 in total capacity WHILE AMBIENT TEMPERATURE IS BELOW 32°F(0°C).
(2) Troubleshooting procedure
When a problem occurs, proceed with troubleshooting in accordance with the procedure shown below.
Problem
Investigate check code
displayed on interface P.C. board
of header unit
(3) If the indoor unit would not produce cool air during cooling mode / would not produce hot air during heating
mode for a long period of time without displaying check code. Do the troubleshooting procedure below.
(a) Check if there's any problem with 4WV3.
(b) Check if there's a problem with PMV-D or PMV-S inside FS unit. (disconnection, coil detachment)
(c) Check if there's a problem with P.C.boards of FS unit Multi-port type. (wiring connection failure, Dip switch
setting, missing P.C.board)
(d) If the problem still persist, check if there's any problem with FS unit (Proceed with FS unit Inspection Mode)
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.
, Outdoor units: MMY-MUP
B
e
h
a
i v
r o
• 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
• It is being operated in timer mode or fan mode.
• It is being in initial communication.
• The air conditioner is being controlled by the cool air discharge preventive
• The air conditioner is being operated in "cooling" under the low outside air
• It is being operated in defrost operation.
• The air conditioner is being controlled by function of residual heat
• The air conditioner is being operated under external or remote control.
"E28" check code
FT
)
P
o
s
temperature.
function in "heating"?
temperature.
elimination being performed as part of the air conditioner shutdown
process after heating operation.
Investigate check code
displayed on interface P.C.
board of relevant follower unit
Any other problem
- 195 -
s
b i
e l
c
a
u
s
e
Check the problem
site or problem part
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Troubleshooting
