Troubleshooting; Overview - Toshiba MMD-AP0481HF2UL Service Manual

10. TROUBLESHOOTING

10-1.

Overview

(1) Before engaging in troubleshooting
(a) Applicable models
All Super Module Multi (SMMS-i, SMMS-e) models.
(Indoor units: MM
(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)
NO.
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 control
(2) Troubleshooting procedure
When a trouble occurs, proceed with troubleshooting in accordance with the procedure shown below.
Check code
Trouble
displayed on interface P.C. board
of header unit
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 control wiring and signal wires as necessary.
∗ ∗∗∗
-AP , Outdoor units: MMY-MAP
Behavior
"E28" trouble
∗∗∗∗
)
• Could it just be the 3-minute delay period (3 minutes after compressor
shutdown)?
• Could it just be the air conditioner having the thermostat set to 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?
• Isn't the outside temp out of range of use temperature?
• 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
control?
Check code
displayed on interface P.C.
board of relevant follower unit
Any other trouble
– 51 –
Possible cause
Check trouble location
or trouble part