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9. TROUBLESHOOTING
9-1. Overview
(1) Before engaging in troubleshooting
(a) Applicable models
All Super Heat Recovery Multi (SHRM-i) models.
(Indoor units: MMO-APOOO, Outdoor units: MMY-MAPOOO4F
∗
)
(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 decline considerably when total operating capacity of cooling indoor units is
less than 38 kBtu/h while ambient temperature is below 32°F (0°C).
(2) Troubleshooting procedure
When a fault occurs, proceed with troubleshooting in accordance with the procedure shown below.
NOTE
Rather than a genuine fault (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.
NO. Behavior Possible cause
1
A compressor would not start • Could it just be the 3-minute delay period (3 minutes after compressor
shutdown)?
• Could it just be the air conditioner having gone thermo OFF?
• Could it just be the air conditioner operating in fan mode or put on the timer?
• Could it just be the system going through initial communication?
• Could it just be within range of use temperature?
When outside temperature is 69.8˚F (21˚C) or higher, heating operation is not available.
When outside temperature is 14˚F (–10˚C) or lower, cooling operation is not available.
2
An indoor fan would not start • Could it just be cold air discharge prevention control, which is part of
heating?
3
An outdoor fan would not start or would
change speed for no reason
• Could it just be cooling operation under low outside temperature
conditions?
• Could it just be defrosting operation?
4
An indoor fan would not stop • Could it just be the elimination of residual heat 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
• Could it just be the air conditioner operation under external or remote
control?
Fault
Any other fault
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 fault site or
faulty part
"E28" error
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