Service manual

CONTROL SYSTEM
11.3.2 Communication with Indoor Units
11.3.2.1 Communication Failures Definition
Two types of communication failures are diagnosed. The communication failures are
checked separately for each IDU channel.
11.3.2.1.1 ‘Bad Communication’ fault
The system keeps a balance of a good/bad communication packet ratio for each active
communication channel.
When the ratio getting high , system enters ‘Bad Communication’
fault.
11.3.2.1.2 ‘No Communication’ fault
If no legal transmission or no message received for 30 seconds, system enters ‘No
Communication’ fault.
When in ‘No Communication’ fault, the system will act as following:
 If there is no
communication in all channels, the following will be performed:
1. The unit changes to SB.
2. The system will scan all the communication.
3. Each channel that is identified as ‘no communication’ channel will be referred as
STBY unit.
4. The unit resumes its normal operation with only the operative channels.
11.3.3 Temperature Measurements
11.3.3.1 Thermistor failures definition
Thermistor Thermistor is Disconnected Thermistor is Shorted
OCT Temp < -40 °C Temp > 75 °C
OAT Temp < -40 °C Temp > 75 °C
CTT Temp < -30 °C Temp > 130 °C
SUCT Temp < -40 °C Temp > 75 °C
HST Temp < -30 °C Temp > 130 °C
RGT Temp < -40 °C Temp > 75 °C
11.3.3.2 System responses for different thermistor failure
Thermistor Default value System Reaction
OCT 6°C
OAT Cool 35°C
Heat 7°C
CTT 43°C Forced compressor to OFF after 20 minutes.
SUCT 6°C
HST 43°C
RGT 43°C
ICT 43°C
11.3.4 Flash Memory Programming
In order to upgrade the ODU software the auxiliary port will be used. A special application
should be run on a PC to transmit the new firmware.
Revision 0
11-5