Hitachi RAF-35NH5 Service Manual page 197

AUTO-FRESH EFROST
¥ uring heating operation is stopped, and when auto-fresh condition is established, defrost operation will be performed while
operation is stopped.
Auto-fresh consists of balancing period at start of defrost for [T F414] seconds
minutes.
(1) Start conditions for auto-fresh
¥ When all the following conditions are established, auto-fresh is executed:
efrost request signal is present.
①
All indoor units are stopped.
②
15 minutes of auto-fresh inhibit period has elapsed.
③
Compressor is ON when operation is stopped.
④
Compressor delay command is sent from indoor unit when operation is stopped.
⑤
(2) Release condition of auto-fresh
¥ If any one of following conditions is established, auto-fresh is released:
Heat exchange temperature returns (heat exchange temperature
①
12 minutes of defrost MAX time has elapsed.
②
Failure occurred.
③
Either unit 1 or unit 2 started operation.
④
Released during start of balancing period : Stopped or started after remaining balancing period has elapsed.
※
Released during reverse cycle period : Stopped or started after balancing for 3 minutes.
(3) Outputs during auto-fresh
[Indoor unit defrost request]: Transmitted only to unit to which auto-fresh is applied (indoor unit stopped last).
[Compressor]: Accelerated by FSTEP min
[Electric expansion valve]:
Unit auto-fresh not applied: FULL CLOSE when balancing for 30 seconds has elapsed at start of defrost.
Unit auto-fresh applied : Synchronized with step-up of rotation speed of compressor, opened by [ FSPPS] pulses and
(4) Note
¥ Shifted to auto-fresh in defrost mode when operation is stopped.
¥ All indoor units must be stopped to fulfill condition for auto-fresh.
If signal is delayed, auto-fresh condition will not be established.
efrosting signal
Unit 1
Unit 2
Unit 1
Unit 2
Unit 1
Unit 2
Turns on for
cooling
Cooling output
Heating output
Outdoor fan
Auto-fresh inhibit period 15min.
WMAX2
Compressor
rotation speed
520
480
Unit 1
0
520
480
Unit 2
100rpm
＋
0
/T FSPT seconds and reaches defrost MAX speed [ EFMAX].
-1
reaches MAX opening degree [ EFSMX] when rotation speed of compressor reaches [ EFMAX].
15sec.
Balancing period [T F414] sec.
WMAX1
60sec. 30sec.
Hold
PCLOSH$
Hold
EFOFF)
≧
efrosting request
Reverse cycle period (max. 12 minutes)
efrosting sequence
30sec. TSKTM2
FSTEP min
T FSPT sec.
S RCT2
FSPPS$ Pulse
Hold
FCTPS$
Hold
- 226 -
Reverse cycle period for MAX 12
→
Balancing period 3min.
EFMAX
/
-1
80sec.
FPSMX$
Balancing request
Balancing request
30sec.