Hitachi RAM-40QH5 Service Manual page 32

AUTO-FRESH DEFROST
During heating operation is stopped, and when auto-fresh condition is established, defrost operation will be
G
performed while operation is stopped.
Auto-fresh consists of balancing period at start of defrost for [TDF414] seconds Æ Reverse cycle period for MAX
12 minutes.
(1) Start conditions for auto-fresh
When all the following conditions are established, auto-fresh is executed:
G
Defrost 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:
G
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
❈ Released during reverse cycle period
(3) Outputs during auto-fresh
[Indoor unit defrost request]
stopped last).
[Compressor]: Accelerated by DFSTEP rpm/TDFSPT seconds and reaches defrost MAX speed [DEFMAX].
[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 [pulses
(4) Note
Shifted to auto-fresh in defrost mode when operation is stopped.
G
All indoor units must be stopped to fulfill condition for auto-fresh.
G
If signal is delayed, auto-fresh condition will not be established.
: Stopped or started after balancing for 3 minutes.
: Transmitted only to unit to which auto-fresh is applied indoor unit
and reaches MAX opening degree [DEFSMX] when rotation speed of compressor
reaches [DEFMAX].
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elapsed.
DEFOFF)