Airwell YAZE218, Service Manual

Page: 40 / 78

SM YAZE218 1-A.2 GB | 11—9
11—CONTROL SYSTEM
11.5 Run Mode
Run mode is the default operation mode of the system. This is the standard operation mode
that is active in eld application (at customer site).
System can go from run mode to other operation modes through keyboard or serial ports.
11.5.1 Mode Setting
Mode de nes the ODU operation mode. There are three possible operation modes:
STBY – standby mode
COOL - the unit operating at cooling cycle
HEAT - the unit operating at heat pump cycle
The ODU de ne the system operation mode according to three methods set by the display key
board:
11.5.1.1 First request priority
The rst IDU which requests different mode than STBY mode will set the new operation mode.
The mode will change once all the units exit the current operation mode.
11.5.1.2 Priority unit
If an IDU is de ned as a priority unit, the operational mode will be de ned according to that unit
request, unless the unit is at STBY mode.
In case priority unit is SB, the mode will be set acceding to rst request priority.
11.5.1.3 Forced operation mode
If forced mode is enabled than the ODU mode will be forced according to the Forced mode
input: Open 7 COOL
Short 7 HEAT
The ODU will go to SB if all the IDU are at SB or at different modes.
11.5.1.4 SB Input
The ODU will change mode between COOL/HEAT and Idle according to the STBY dry contact
input as follows:
STBY input ODU mode
B S tr o h S
Short 7 Open last mode
Open according normal mode selection
11.5.2 Compressor Speed Control
11.5.2.1 Compressor Min On/Off time
Compressor minimum OFF time is MinOFFTime minutes except during Deicing protection.
Compressor minimum ON time is MinOnTime minutes, minimum ON time is ignored during
protections, and when unit is turned to STBY.