AEXM24HR
2 – 3
     compressor is stopped, if the temperature is below 85°C,another
     starting try will be made. Three retries are allowed. On the fourth 
     retry, a complete stop request signal is sent to the indoor unit, 
     and the outdoor unit will remain stopped until the indoor operation is
     stopped. 
1.5. SERIAL SIGNALS 
 Serial signals consist of all 96-bit signals. 
 If the condition as outdoor unit unable to receive a serial signal from 
 the indoor unit continues for 30 seconds, it closes the expansion  
valve which corresponds to the room which can not be communicated. 
  If all indoor units can not communicate with the outdoor unit,
  the compressor is stopped. 
1.6. THERMISTOR OPEN OR SHORT 
  When compressor, heat exchanger, outdoor thermistor,
  suction thermistor (CN8A) are in OPEN or SHORT condition,even if
  they are in the condition which an operation signal is transmitted from 
  indoors, the compressor will not start.  If any suction thermistors 
  (CN8C) become  OPEN or SHORT resistance, the protective
  procedure will work only for the cycle corresponding  to the
  malfunctioning suction thermistor. 
1.7. MISWIRING CHECK 
"Miswiring check" is conducted by detecting the indoor heat exchanger
indoor heat exchanger temp. 
For example, when the expansion valve for only room A is open,
and the wiring is correct, the indoor heat exchanger temp for room
A will reduce. 
If the wiring is incorrect, the indoor heat exchanger temp for a  different 
 room will reduce. 
1.8. SAFETY TIME
When the unit is operated by the remote control after the breaker is
turned on, the safety device of the compressor will work and the 
 compressor will not  operate for 90 seconds.
 
1.9. PUMP DOWN SWITCH 
When the PUMP DOWN SWITCH (SW1) is pressed for 5 seconds or
more, the total A/C system will start its TEST RUN automatically and
the compressor frequency will be 55 Hz. 
When operating only the outdoor unit (cooling 55Hz fixed mode)  to
make only the outdoor unit run in cooling mode,and apply a voltage 
of 230 V AC to N and L on the terminal board and push the PUMP 
DOWN SWITCH. (SW1) (Avoid operating the outdoor unit alone for
long  periods of time.) 
1.10. CONTROL OF COMPRESSOR OR AND EXPANSION
VALVE
For 90 seconds after turning on the AC power, the compressor will not 
 be activated even if indoor units request the compressor to do so.
 If the compressor receives a request from one or more indoor units
 indoor units after 90 seconds have passed, it will be turned on and the 
 expansion valve corresponding to the requesting indoor unit will be
 opened. 
When the indoor unit of a room requests for the cooling operation to
the outdoor unit and it runs responding to the request,
requests for the heating can't be accepted if the indoor units  in other
 rooms send individual requests. 
If the indoor unit in another room sends a request for the heating
operation, the operation lamp and timer lamp of the indoor unit in that
 room start flashing in turn to inform that the unit is in the  standby
 mode. 
If the operation in one room is stopped while the indoor unit in another
 room is in the stand-by mode, 
the operation mode requested by the indoor unit 
which is now in the stand-by mode will be accepted. 
At this time, the compressor will be temporarily 
stopped to switch the four-way valve and restart after 90 seconds. 
During the cooling or dry operation, the expansion valve 
corresponding to the indoor unit that is not running is closed. 
Therefore, the  refrigerant will not flow into those units.
However,if the heating operation is in progress, it is possible that it
flows into indoor units which are out of operation depending on the
cycle conditions. 
As a result, the indoor exchanger may be heated up even if it is not 
activated. This is not abnormal. 
When the operations in all rooms are stopped, the compressor is
stopped,the expansion valves in all rooms are fully opened. 
1.11. DEFROST OPERATION 
(1) Overview 
Defrosting begins during heating if the conditions for compressor 
operation time and outdoor heat exchanger temperature  are met. 
When defrosting begins, the indoor and outdoor fans stop. 
Defrosting stops when the temperature of the outdoor heat exchanger
goes above approximately 15°C.or defrosting time exceeds 10
 minutes. 
(2) Defrosting 
If the compressor operation time is more than 20 minutes in the 
 heating mode and the outdoor air temperature and outdoor heat
 exchange temperature satisfy the defrosting conditions,
 the defrosting operation is started. 
When the defrosting operation is started, the indoor fan starts to run 
intermittently. 
When the outdoor heat exchanger temperature reaches approx. 15°.C 
 or above or when the defrosting time exceeds 10minutes, 
 the defrosting operation is quit.
Defrost
mask time
Defrost
mask time
Defrost
mask time
Heating
begins
Defrosting
Max. 10 min.
Defrosting
Max. 10 min.
Defrost
mask time
Defrost
mask time
Defrost
mask time
Heating
begins
Defrosting
Max. 10 min.
Defrosting
Max. 10 min.