Defrost Control (Only In Heating Operation); Start Of Heating Operation - Toshiba RAS-18J2KVSG-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

Table 1
Defrost zone In normal To
A zone TE0-TE≥3°C & SH-SH0≤2
B zone TE0-TE≥2°C & SH-SH0≤2
C zone
D zone
More than 90 minutes accumulate heating operation time condition TE≤ -2°C
Table 2
Heating operation
18k
(time)
a
b
c
d
Operation flow and applicable data, etc.
b,c a
In abnormal To
(TE0-TE)-(TO0-TO)≥3°C & SH-SH0≤2
(TE0-TE)-(TO0-TO)≥2°C & SH-SH0≤2
TE≤ -25°C & SH-SH0≤2
Model
24k
22k
43 41
41 39
29 29
90 70
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.
d
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 exchanger
rises to +8°C or higher.
2)Temperature of outdoor heat exchanger is
kept at +5°C or higher for 80 seconds.
3) Defrost operation continues for
15 minutes.
<Returning from defrost operation>
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.
- 41 -
Description