Airwell YAZE218, Service Manual

Page: 43 / 78

11—12 | SM YAZE218 1-A.2 GB
11—CONTROL SYSTEM
11.5.3 EEV Control
11.5.3.1 Operation Range
The EEV operation range is de ned according to the operation mode as following
ODU Mode Normal operation IDU inactive Compressor off
0 0 4 B S
400 COOL 50 to 480 0
HEAT 50 to 480 50 to 120
11.5.3.2 Reaching target value rules
For all cases except at EEV initialization procedure, each EEV can move no more than 20
steps at a time.
When required the EEV’s move, one by one in sequence, until the target position is achieved
for every EEV.
The following diagram presents the EEV steps until the target position is set.
EEV1 EEV2 EEV3 EEV4 EEV1 EEV3 EEV4 EEV3 EEV4 EEV3 EEV3
EEV2 set EEV1 set EEV4 set EEV3 set
11.5.3.3 EEV homing
When compressor stops or unit is power on, the following is performed immediately:
— All EEV’s are set to 400.
— They remain in this position for 80 Sec.
— Then, close to 60 steps below 0 to ensure full closure, then proceed to normal operation
11.5.3.4 EEV Opening Determination
The target EEV value is the sum of open loop value (OL) and a result of the accumulative
correction values (CV).
EEVi = ∑ EEVCVi
EEVi is the EEV opening for each ‘i’ IDU.
11.5.3.5 EEV initial value determination
The EEV initial value (open loop) is determined according to the number of the active indoor
units, mode, and the capacity code of the unit.
11.5.3.6 Balance time
During the rst 5 minutes after SB, the correction is not calculated. After that, the correction
value is updated every 30 seconds.
11.5.3.7 EEV corrections
The corrections in cool mode will keep the compressor in the proper operation temperature
and will balance between the indoor units by controlling their super heat.