Toshiba RAV-GM301ATP-E Service Manual page 43

Item
7. Defrost control (This function removes frost adhered to the outdoor
(Only in heating heat exchanger.)
operation)
The temperature sensor of the outdoor heat ex-
changer (Te sensor) judges the frosting status of the
outdoor heat exchanger and the defrost operation is
performed with 4-way valve reverse defrost system.
Start of heating operation
0' 10' 15'
a°C
b°C
c°C
*
Te0 detection time
Model
a
−5
GM30
GM40
−3
* The minimum value of Te sensor 10 to 15 minutes after start of
operation is stored in memory as Te0.
When Te0 - TE ≥ 2.5 continued for 2 minutes in A zone,
A zone
defrost operation starts.
When the operation continued for 2 minutes in B zone,
B zone
defrost operation starts.
When Te0 - TE ≥ 3 continued for 2 minutes in C zone,
C zone
defrost operation starts.
Operation flow and applicable data, etc.
Operation time
29' 35'
(Minute)
C zone
A zone
B zone
b
−7
−7
Table 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, or C zone each. (Table 1)
<Defrost operation>
• Defrost operation in A to C zones
1) Stop operation of the compressor for
20 seconds.
2) Invert (ON) 4-way valve 10 seconds
after stop of the compressor.
3) The outdoor fan stops at the same
time when the compressor stops.
4) When temperature of the indoor heat
exchanger becomes 38°C or lower,
stop the indoor fan.
<Finish of defrost operation>
• Returning conditions from defrost
operation to heating operation
1) Temperature of outdoor heat ex-
changer rises to +8°C or higher.
2) Temperature of outdoor heat ex-
changer is kept at +5°C or higher for
80 seconds.
c
3) Defrost operation continues for
15 minutes.
−20
<Returning from defrost operation>
−26
1) Stop operation of the compressor for
approx. 50 seconds.
2) Invert (OFF) 4-way valve approx. 40
seconds after stop of the compressor.
3) The outdoor fan starts rotating at the
same time when the compressor starts.
– 43 –
FILE NO. SVM-18042-1
Description