Electra DNC series Service Manual page 74

2.4.2
2.5. HE operation
2.5.1 Minimum Heaters ON or OFF time is 30 sec.
2.5.2 Heaters can be activated only if IFAN is on.
2.5.3 In RH group, HE-1 and HE-2 will be activated only when COMP (or
WVL) is not operating, except in Dry Mode.
2.6. Protections
2.6.1 High pressure protection is applicable to all operating modes.
2.6.2 Deicing control is valid in Heat and Auto Heat Mode only.
2.6.3 Defrosting control is valid in Dry, Cool, Heat and Auto Modes.
2.6.4 No reset after protection modes.
2.7. Thermistors operation
2.7.1 Return air Temp. is detected by RAT (RT1) in normal Mode, or by
RCT (R/C sensor) in I-FEEL Mode.
2.7.2 Indoor Coil Temp. is detected by ICT (RT2).
2.7.3 Outdoor Coil Temp. is detected by OCT (RT3).
Similarly, in the Indoor Units of a WMQ/T system, 4.7k Ohm (5%)
resistors must be connected to the OCT ports to disable the
"Thermistor Temp reading doesn't change" error checking.
2.7.4 Definition of thermistor faults:
a. Thermistor is disconnected -
The thermistor reading is below -30
b. Thermistor is shorted -
The thermistor reading is over 75
c. Thermistor Temp reading doesn't change (irrelevant for RT1)
-
(i) 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 & OCT are compared with those
when the COMP was switched from OFF to ON 10
min before. If the ∆T is less than 3
is regarded as defective.
(ii) The ICT and OCT no-change error can be disabled
together by connecting a 4.7 k or 3.9 k ohm resistor
(5%) to the OCT connector. These resistors are
equivalent to a thermistor at 43+/-1
respectively.
2.7.5 Cases for disabling thermistor short/disconnected detection
i. The detection of thermistor faults (a) and (b) above, are 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.
ii. When all the following conditions are fulfilled:
a. 4.7K Ohm resistor is connected on the OCT
b. IFAN is OFF
c. Compressor is ON
Service Manual - DNC Series
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c.
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c.
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c, the thermistor
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c and 48+/-1
Revision Y05-01
CONTENT
CONTROL SYSTEM
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