Troubleshooting; Overview - Carrier MMY-MAP0724FT9UL Service Manual

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)
NO. Behavior
A compressor would not start
1
An indoor fan would not start
2
An outdoor fan would not start or would
change speed for no reason
3
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 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.
Investigate check code
Fault
displayed on interface P.C. board
of header unit
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.
• 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.
• 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
control?
"E28" error
Investigate check code
displayed on interface P.C.
board of relevant follower unit
Any other fault
– 129 –
∗
)
Possible cause
Check fault site or
faulty part