Haier AP48KN1EAA Service Manual page 38

Single Split
2.4 Manual defrost
Indoor sends defrost signal to outdoor, and the outdoor will receive the defrost signal when
compressor is running in heating mode, then enter the defrost process. When outdoor coil
temperature arrives the defrost-end point and the defrost time is over 5 minutes, outdoor will send
the defrost-end signal to finish the defrosting.
3. Compressor crankcase heater working condition
By the N.C. (normal close) auxiliary point of AC contactor to control, when compressor stops, the
heater will work; when compressor works, the heater will stop.
4. System protection function
4.1 Anti-freeze protection
When compressor has run for over 6 minutes, to prevent indoor evaporator freezing (in cooling/dry
mode), if indoor coil temp. is below -1 degree for over 1 minutes, compressor and outdoor motor will
stop and enter Fan mode. After compressor stops for 9 minutes, and indoor coil temp. rises up to 10
℃ , the unit resumes to cooling mode, compressor and outdoor motor will work again.
4.2 Overheat protection
In heating mode, if indoor motor is running and the compressor has run for over 30 seconds, the
sensor will check the indoor coil temperature, and send the temp. to outdoor; if indoor coil temp.
>T1（56 ℃）, the outdoor motor will enter low speed; If indoor coil temp. ＜ T2（52 ℃）, outdoor
motor will enter high speed; if indoor coil temp. >T3（60℃）, outdoor motor will stop; if indoor coil
temp. ＜ T4（56℃）and the outdoor fan stop over 5 seconds, outdoor motor will resume low speed;
When indoor PCB receive the signal of outdoor motor stop from outdoor PCB over 2 minutes, if
indoor coil temp. >T6（70℃）or 10 minutes later indoor coil temp. >T5（56℃）, send compressor
stop signal to outdoor unit; if indoor coil temp. ＜ 46 ℃ and the compressor has stopped over 3
minutes, send compressor run signal to outdoor unit, and compressor resume to normal. The
outdoor motor is control by outdoor unit.
4.3 Over current protection
(1) In heating mode
After compressor running for 40 seconds, if the current thermostat has measured that system
working current is more than 21A and keep it for 5 seconds, outdoor motor will convert into low
speed; if working current is less than 18A, it will resume to high speed; if working current is more
than 24A and keep it for 5 seconds, outdoor motor will stop; if working current is less than 22A,
outdoor will resume to low speed (fan speed conversion frequency must be more than 45 seconds);
after compressor running for 40 secends, if working current is more than 34A and keep it for 5
seconds, compressor will stop and will resume 3 minutes later.If within 30 minutes there are 3 times
compressor over current protection, compressor will not start up, meanwhile, LCD will display E5.
Only shut off and powered on again, the protection can be cancelled.
(2) Not in heating mode
After compressor running for 5 minutes, if working current is more than 34A and keep it for 5
seconds, compressor will stop and will resume 3 minutes later.
If within 30 minutes there are 3 times compressor over current protection, compressor will not start
up, meanwhile, LCD will display E5. Only shut off and powered on again, the protection can be
cancelled.
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