Airwell K XLN24 RC 3PH, Technical Manual

Page: 41 / 82

CONTROL SYSTEM
11-6 Revision 0
11.3.5 Protections
a. High pressure protection is applicable to all operating modes.
b. Deicing control is valid in Heat and Auto Heat Modes only.
c. Defrosting control is valid in Dry, Cool, and Auto Cool Modes.
11.3.6 Thermistors Operation
a. Return air Temp. is detected by RAT in normal Mode, or by RCT (R/C sensor) in
I-FEEL Mode.
b. Indoor Coil Temp. is detected by ICT.
c. Outdoor Coil Temp. is detected by OCT.
d. Definition of thermistor faults:
1) Thermistor is disconnected - the thermistor reading is below – 30
O
C.
2) Thermistor is shorted - the thermistor reading is above 75
O
C.
3) Thermistor Temp reading doesn’t change -
a) This test is performed only once after a unit is switched from OFF/STBY
to operation. At the first occurrence of 10 min continuous COMP
operation, the current ICT are compared with those when the COMP was
switched from OFF to ON 10 min before. If the
∆
T is less than 3
O
C, the
thermistor is regarded as defective.
b) The ICT no-change error can be disabled together by connecting a 4.7k
Ω
resistor (5%) to the ICT connector. These resistors are equivalent to a
thermistor 48+/-1
O
C.
e. Cases for disabling ICT thermistor disconnected detection:
1) The detection of thermistor faults a. and b. above is disabled when Deicer
Protection is started. The detection will be enabled again only after (1) the
deicing is completed, and (2) COMP has been restarted and operated for 30
sec.
2) When all the following conditions are fulfilled:
a) 4.7k
Ω
resistor is connected to the OCT.
b) IFAN is OFF.
c) Compressor is ON.
d) ICT < -30 (disconnected).