Toyotomi MTN-MTG 256DV Service Manual page 21

When indoor fan speed is too low (lower than 300rpm for 50 seconds), the unit will stop and LED display error
code and can't return to normal operation automatically.
9.3.6 Protection of outdoor fan speed.
When outdoor fan speed is lower than 300rpm or higher than 1500rpm for 60 seconds, the unit will stop and
LED display error code and can't return to normal operation automatically.
9.3.7 Inverter module Protection.
Inverter module has a protection function against current, voltage and temperature. If these protections
happened, the unit will stop and LED display error code .
9.3.8 Indoor fan delayed open function.
When the unit is turned on at all modes, the indoor fan will operate 10 seconds later than the action of louver.
9.3.9 EEPROM parameter error.
9.3.10 Communication error between indoor and outdoor units.
When outdoor unit doesn't receive communication signal from indoor unit for 2 minutes, the unit will stop
compressor and display error code, stop outdoor fan 30 seconds later and stop 4 way valve 2 minutes later.
9.3.11 Communication error between main chip and compressor driving chip of outdoor units.
When main chip and compressor driving chip don't receive communication signal from each other for 1 minutes,
the unit will stop compressor and display error code.
9.3.12 Compressor preheating function.
1)Preheating permitting condition:
If T4(outdoor ambient temperature) 3
compressor has stopped for over 3 hours, the compressor heating cable will work.
2)Preheating mode:
A weak current flows through the coil of compressor from the wiring terminal of compressor, then the compressor
is heated without operation.
3)Preheating release condition:
If T4 5 or user turns on the machine and compressor runs, preheating function will stop.
9.3.13 Frequency limit protection against low voltage.
VDC
VOLT_RST1_ADD
VOLT_LIM1_ADD
VOLT_RST2_ADD
VOLT_LIM2_ADD
and the machine connects to power supply newly or if T4 3
Normal working frequency
VOLT_LIM_FREQ1_ADD
VOLT_LIM_FREQ2_ADD
and
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