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9
Troubleshooting
9-1. Overview
(1) Before engaging in troubleshooting
(a) Applicable models
Indoor units: MMO-APOOO, Outdoor units: MCY-MHPOOO4
(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)
(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.
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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?
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
controllerl?
Fault
Investigate check code displayed on
interface P.C. board of outdoor unit
Check fault site or
faulty part
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