Troubleshooting; Overview - Toshiba MCY-MHP0404HS-E Service Manual

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)
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
(2) Troubleshooting procedure
When a trouble occurs, proceed with troubleshooting in accordance with the procedure shown below.
NOTE
Rather than a genuine 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.
AMP Air Conditioning
B e h a i v r o
trouble
Investigate check code displayed on
interface P.C. board of outdoor unit
P o s
Could it just be the 3-minute delay period (3 minutes after compressor
shutdown)?
Could it just be the air conditioner having gone thermostat 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 cold air discharge prevention control, which is part of
heating?
Could it just be cooling operation under low outside temperature
conditions?
Could it just be defrosting operation?
Could it just be the elimination of residual heat being performed as part of
the air conditioner shutdown process after heating operation?
Could it just be the air conditioner operation under external or remote
controllerl?
Check trouble site or
trouble part
95
108
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