Control Features - Toshiba MAR-C104M8-1-PE Service Manual

NO. CONTROL
Defrost
1
(Heating mode)
Does not apply to
MAR-C104M8-1-PE
2 Oil Retrieval
(Cooling mode)
3 Superheat control
(Cooling mode)

9. CONTROL FEATURES

DESCRIPTION
• During heating operation, defrost is
controlled by the Outdoor unit heat exchanger
temperature sensor (TE).
• When the cumulative operating time with TE
in zone [A] has amounted to 25 minutes,
defrost operation starts. Subsequent
defrosts occur after a cumulative time of 55
minutes. When heating operation resumes
after defrost, the timer is reset.
• The maximum defrost period after TE returns
to zone [B] is 1 minute.
• Heating operation resumes immediately after
TE returns to zone [C].
• During cooling operation, oil retrieval is
performed if one or more Indoor units are
OFF.
• If this condition is satisfied, when cooling
operation commences, oil retrieval takes
place for 1 minute.
If cooling operation continues, oil retrieval is
repeated for 1 minute every 60 minutes.
•
During oil retrieval the following occurs:
a. All Multi controller PMV's are opened.
The degree of opening is dependant
on the capacity of the Indoor unit .
b. If the D.O.L. compressor is OFF the
inverter compressor speed increases
to SD.
• When cooling operation ends the timer is
reset.
• Superheat is controlled by the Multi controller
for cooling operation.
The level of superheat is determined by the
difference between the evaporator outlet
temperature for each Indoor unit
(ThA, B, C, D) and the saturation temperature
(ThX).
• If the superheat of an Indoor unit enters zone
[Y], the relevant M/C PMV opens further to
compensate for this increase. The degree of
additional opening is dependant on the
capacity of the Indoor unit.
• When zone [Z] is reached the PMV
opening is held at the level set in zone [Y].
• When the level of superheat returns to zone
[X] the control is cancelled.
Temp.
(°C)
1 min.
Oil
retrieval
Superheat
(°C)
53
DIAGRAM
C
12
B
8
-3
A
Cooling mode
60 min.
< 60 min.
1 min.
Oil
retrieval
Y
13
Z
9
X
Compressor
off
Timer
reset