Cases For Disabling Thermistor Short/Disconnected Detection; Handling The Thermistor Faults In A Comp Unit - Electra WNG 7 Service Manual

CONTROL SYSTEM
12.4.6.2

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
d. ICT < -30 (disconnected)
This condition come to detect and prevent IFAN operation in Deicer in multi spilt
units.
12.4.6.3

Handling the thermistor faults in a COMP unit

i. ICT/OCT thermistor is disconnected or shorted -
The invalid thermistor temperature is replaced by 43
can continue the normal operation. All protections related to that faulty
thermistor will be disabled. For example, in case of any ICT fault, the ICT
high pressure protection in Heat Mode and ICT defrost protection in Cool
Mode will not operate anymore. The same is also applied to the OCT fault.
ii. RAT thermistor is disconnected or shorted –
The RAT will be derived from the ICT by using the equations :
Notes:
•
In case of any thermistor failure, the STBY LED will be blinking until the
fault condition is corrected.
•
User can use the system diagnostics function to find out the nature of
the thermistor faults.
i. RAT thermistor is disconnected or shorted –
System will operate continuously in the last IFAN & WVL status when
turned ON.
Notes:
•
As in the COMP unit, the STBY LED will be blinking to indicate a
thermistor fault. And, the user can use the system diagnostics function
to find out the nature of the fault.
12-6
Heat Mode: RAT=ICT/2.3
Cool Mode RAT=ICT*4
Revision Y05-03
CONTENT
o c, so that the unit
Service Manual - WNG