Service manual

15-12
CONTROL SYSTEM > GC 24
SM HADDCI 1-A.2 GB
15.4.15.3 Protection Behavior
When in total IDU protection level is different than normal, the OFAN will reduce
• OFSpdReducePrtC and
OFSpdReducePrtH RPM for cool and heat respectively.
In cool mode the OFAN will operate according to CTT or HST protection level:
•
Protection level Action
SR, D1 or D2 OFAN will add 100 RPM to the target speed
Stop-Compressor continue to operate for maximum 2 minutes at it last speed or until normal level is achieved.
15.4.15.4 OFAN Force On condition
If HST is higher than 70°C or defined as “HST bad”, OFAN will remain ON at the last operating speed for
maximum 2 minutes after COMP is OFF.
15.4.15.5 Night mode
Upon receiving night mode, the OFAN will be limited to max NightRPM speed only in Cool. It will be back to its
normal operation when receiving the mode is cleared.
15.4.16 RV State Setting
During heat mode (except during Deicing) RV is ON. During cool/SB mode RV is OFF.
RV status will be changed only if COMP is OFF for 3 minutes or more.
15.4.17 Base Heater Setting
The base heater will be working only when RV is “ON” according to the following graph:
When OAT is faulty the base heater will be “ON” continuously in HEAT mode.
15.4.18 Thermodynamic Protections
15.5.18.1 Protection level definition
Five protection levels are defined:
Normal - No protection status is ON.
Stop-Rise (SR) - System is in protection, first level
D1 - System is in protection, second level
D2 - System is in protection third level
Stop-Compressor (SC) - System is in protection fourth level
15.4.18.2 IDU Protection Level
The ODU receives the protection levels from the IDU. The protection levels are weighted according to the
following table:
Protection Level Weight
Normal 0
Stop-Rise 1
D1 2
D2 3
Stop-Compressor 0
ON
OFF
OAT
0
2
Base
Heater
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