Sanyo CHDXR09663* Service Manual page 17

4. Special Controls
4-3-6. Outdoor unit cycle defrost
Outdoor unit cycle defrost is performed in systems where 2 outdoor units are connected to the refrigerant system.
(1) Description of outdoor unit cycle defrost
With this defrost method, when 1 outdoor unit operates in defrost mode (heat exchanger operating as a con-
denser), another outdoor unit operates as an evaporator in the same way as in ordinary heating mode.
In this way, the other outdoor unit is heating the unit where defrost is occurring. When 1 outdoor unit completes
defrost, the other outdoor unit performs defrost in the same way.
1
Because the amount of time that the unit operates as an evaporator is very short, there is little danger of frost
forming again quickly. Rather, because the heat source is very powerful, it is possible to shorten the defrost
operating time.
(2) Defrost sequence
Outdoor unit cycle defrost is always completed in 2 defrost operations.
(A) When there are 2 outdoor units
• Defrost flow
Outdoor unit(s) where defrost occurs first
Outdoor compressor(s) where defrost occurs first
Outdoor unit(s) where defrost follows later
Outdoor compressor(s) where defrost follows later
Stopped indoor unit(s)
Indoor units where fan is operating
Heating mode indoor
units
Defrost Evaporator
outdoor unit outdoor unit
First operation
E: Evaporator operation
C: Condenser operation
S: Shut off
E C: Switching from evaporator operation to condenser operation
C E: Switching from condenser operation to evaporator operation
Defrost
preparation
Thermostat ON
Thermostat OFF
1 min
Time
Switch
Evaporator
outdoor unit
Second operation
Defrost in
progress
C
E C
OFF ON
E
E
Defrost
ON ON
end
S
S
judgment
S
S
C
C
C C
Max. 6 min
1 - 12
W-2WAY ECO-i SYSTEM
Control Functions
Defrost
outdoor unit
Defrost in
Switch
progress preparation
C E E
OFF ON
E C
C C
Defrost
OFF ON
end
S S
judgment
S S
C C
C C
1 min Max. 6 min
Defrost
E or S
OFF
E or S
OFF
S
S
C
C
1 min