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Item Operation flow and applicable data, etc. Description
7. Defrost control
(Only in heating
operation)
(This function removes frost adhered to the outdoor
heat exchanger.)
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.
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 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.
Table 1
* The minimum value of Te sensor 10 to 15 minutes
after start of operation is stored in memory as Te0.
A zone
B zone
C zone
When (TE0 - TE) - (TO0 - TO) ≥ 3°C and SH-SHO ≤ 2
in A zone, defrost operation starts.
When TE ≤ -25°C and SH-SHO ≤ 2 in C zone,
defrost operation starts.
FILE NO. SVM-14017
D zone
More than 70 minutes accumulated heating
operation time condition TE < -13°C
When (TE0 - TE) - (TO0 - TO) ≥ 2°C and SH-SHO ≤ 2
in B zone, defrost operation starts.
•
Strong defrost
Upgrade defrost ability when normal defrost ability
is not enough by increase defrosting finished
operation.
<
Finish of defrost operation for strong
defrost
>
•
Do cut the jumper J803 on CDU PCB
Returning conditions from defrost
operation to heating operation
1)
Temperature of outdoor heat exchanger
rises to +13°C or higher.
2)
Temperature of outdoor heat exchanger is
kept at +10°C or higher for 80 seconds.
3)
Defrost operation continues for
20 minutes.
•
*
-3°C
-7°C
-25°C
-13°C
0' 10' 15'
29'
70'
Start of heating operation
A Zone
B Zone
35'
C Zone
D Zone
Operation time
(Minute)
Outdoor heat exchanger temperature
J804
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