12-6
CONTROL SYSTEM
SM HAFRPM 2-A.1 GB
(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
o
c and 48+/-1
o
c respectively.
(iii) Connecting a 4.7k resistor to the ICT connector will disable the ICT no-change
error only.
Cases for disabling thermistor short/disconnected detection
1. 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.
2. 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.
Handling the thermistor faults in a COMP unit
i.
ICT/OCT thermistor is disconnected or shorted -
The invalid thermistor temperature is replaced by 43
o
c, so that the unit 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.
There is an EEPROM option that, when the OCT thermistor is not connected, the
buzzer will be ON continuously until the user turn off the alarm by
(i)
switching the unit to STBY using a R/C, or
(ii)
pressing the mode switch once.
Once the alarm is turned OFF, it will not be active again unless the unit is reset.
ii.
RAT thermistor is disconnected or shorted –
The RAT will be derived from the ICT by using the equations :
Heat
Mode:
RAT=ICT/2.3
Cool Mode: RAT=ICT*4
Notes:
1. In case of Shorted/Disconnected thermistor failure, the STBY LED will
be blinking until the fault condition is corrected. In case of “Temp No
change” fault the STBY LED will never blink.
2. User can use the system diagnostics function to find out the nature of
the thermistor faults.
Notes:
1. 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.
