High Wall, Heat Pump Type
Service Manual
40
Toshiba
8-7-2. In heating operation
Prevent-overpressure control for refrigerating
cycle
In heating operation, the sensor of indoor heat
exchanger detects condensation temperature and
controls the compressor speed so that temperature of
the heat exchanger does not exceed the specified
value.
1) When temperature of the indoor heat
exchanger rises in the range from 52°C to
55°C, the compressor speed is kept.
(Q zone)
When temperature of the indoor heat
exchanger drops in the range from 48°C to
under 55°C, the compressor speed is kept.
(Q zone)
2) When temperature of the indoor heat
exchanger rises to 55°C or higher, the
compressor speed is reduced. (P zone)
3) When temperature of the indoor heat
exchanger does not rise to 52°C, or when it
drops below to 48°C, the capacity control
operation returns to the usual control in heating
operation.
(R zone)
8-8. Defrost Control (Only
in Heating Operation)
This function removes frost adhered to the
outdoor heat exchanger.
The temperature sensor of the outdoor heat exchanger
(TE sensor) judges the frosting status of the outdoor
heat exchanger and the defrost operation is performed
with 4-way valve reverse defrost system.
* The minimum value of TE sensor 10 to 15 minutes
after start of operation is stored in memory as TE0.
Table 8-8-1
The necessity of defrost operation is detected by the
outdoor heat exchanger temperature. The conditions
to detect the necessity of defrost operation differ in A,
B, C or D zone each. (Table 8-8-1)
8-8-1. Defrost Operation
Defrost operation in A to D zones
1) The compressor stops for 40 seconds.
2) The 4-way valve is switched to the cooling
position 30 seconds after the compressor
stops.
3) The outdoor fan stops at the same time when
the compressor stops.
4) The indoor fan stops after temperature of the
indoor heat exchanger becomes 38°C or lower.
55°C
52°C
48°C
P
Q
R
Reduction of compressor speed
Usual heating capacity control
Indoor heat e
xchanger temper
ature
When the value is
in Q zone, the
compressor speed
is kept.
A zone
When TE0 - TE
≥
2.5 continued for 2 minutes in A zone,
defrost operation starts.
B zone
When the operation continued for 2 minutes in B zone,
defrost operation starts.
C zone
When TE0 - TE
≥
3 continued for 2 minutes in C zone,
defrost operation starts.
D zone
When the operation get into D zone, defrost operation
starts.
–3°C
0’
Operation time
(Minute)
Start of heating operation
TE0 detection time
*
Outdoor heat exchanger temperature
C zone
D zone
A zone
B zone
–7°C
–11°C
–26°C
10’ 15’
37’
90’
+00A08-010_01EN_SVM_HighWallHeatPump.book Page 40 Wednesday, March 4, 2009 11:22 AM
