12-18
CONTROL SYSTEM
Revision Y05-01
Service Manual - ALPHA
12.9 Protection
12.9.1 Cooling
Mode
Protections
Indoor Coil Defrost
Mode:
Cooling,
Dry,
Auto
Temp:
Selected
desired
temp.
Fan:
Any
Timer:
Any
I
Feel:
On
or
Off
Control
Function
Protect the indoor coil from ice formation at low ambient temperature.
t1 = 5 min minimum for each COMP starting
t2 = OFAN cycling (alternate between ON and OFF every 30 sec) for 20 min
maximum
t3 = COMP and OFAN stop for 10 min minimum
Notes:
•
When J7 is closed (connected), OFAN cycling is cancelled and the
set temperature for COMP & OFAN cut-out and cut-in are changed.
COMP & OFAN are forced OFF when ICT =< -6
o
c, and are kept OFF
until ICT > 14
o
c.
•
For WAX model, the defrost processes is simpler. When J7 is open,
COMP & OFAN are forced OFF when ICT =< -1
o
c, and are kept OFF
until ICT > 5
o
c. When J7 is closed, the WAX defrosting process is the
same as that of the other models (R.H.S. of the graph above). In both
cases, the ICT checking in t2 and t3 are not applied.
ICT [
o
c]
+2
ON
OFF
ON
OFF
t1
t2
t3
COMP
OFAN
+1
+5
+14
0
-1
-6
ON
OFF
IFAN
J7 OPEN
J7 CLOSED
t1
t1
