Defrost Control (Only In Heating Operation) - Toshiba RAS-B07G3KVSG-E Service Manual

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
* The minimum TE value and To value between 10 and 15 minutes after heating operation has
started are stored in memory as TE0 and TO0, respectively.
Table 1
Defrost zone
A zone
B zone
C zone
D zone
Table 2
Heating operation
(time)
a
b
c
d
<Defrost operation>
• Defrost operation in A to C zones
1) Stop operation of the compressor for
40 seconds.
2) Invert (OFF) 4-way valve 40 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 exchanger
rises to +8°C or higher for 3 seconds.
2) Temperature of outdoor heat exchanger
is kept at +7°C or higher for 60 seconds.
3) Defrost operation continues for
10 minutes.
Operation flow and applicable data, etc.
In normal To
TE0-TE≥3°C & SH-SH0≤2
TE0-TE≥2°C & SH-SH0≤2
More than 90 minutes accumulate heating operation time condition TE≤ -2°C
Model
07k 13k
10k
43 51
39 49
31
90
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)
b,c a
(TE0-TE)-(TO0-TO)≥3°C & SH-SH0≤2
(TE0-TE)-(TO0-TO)≥2°C & SH-SH0≤2
TE≤ -25°C & SH-SH0≤2
16k
<Returning from defrost operation>
1) Stop operation of the compressor for
approx. 40 seconds.
2) Invert (ON) 4-way valve approx. 30
seconds after stop of the compressor.
3) The outdoor fan starts rotating at the
same time when the compressor starts.
- 40 -
Description
d
In abnormal To