Midea M2OC-18HFN1-M Service Manual page 14

---- When outdoor fan speed is lower than
300RPM or higher than 2400RPM for 60 second,
the whole unit stops and LED displays failure.
7.3.4 Inverter module Protection.
----Inverter module protection itself has a
protection function against current, voltage and
temperature. If these protections happened, the
corresponding code will display on indoor unit
LED and A/C will stop. The unit will recover 3min
delay after the protection disappeared.
7.3.5 Low voltage protection
VOLTAGE
VOLT_RST1_ADD
VOLT_LTM1_ADD
VOLT_RST2_ADD
VOLT_LTM2_ADD
Note: if the low voltage protection occurs and not
resumes within 3min, it will keep the protection
always after restart the machine.
7.3.6 Compressor current limit protection
If the compressor current exceeds the current
limit value for 10 seconds, the compressor
frequency will be limited as below table.
Cooling mode:
Current Current limit
frequency(Hz) value(A)
COOL_F16 ICOOLLMT12
COOL_F15 ICOOLLMT11
COOL_F14 ICOOLLMT10
COOL_F13 ICOOLLMT9
COOL_F12 ICOOLLMT8
COOL_F11 ICOOLLMT7
COOL_F10 ICOOLLMT6
COOL_F9 ICOOLLMT5
COOL_F8 ICOOLLMT4
COOL_F7 ICOOLLMT3
COOL_F6 ICOOLLMT2
No limit
VOLT_LTM_FREQ1_ADD
VOLT_LTM_FREQ2_ADD
Frequency limit
Decrease the frequency to
COOL_F4 and run at COOL_F4
for 3 minutes.
After that, the frequency will be
adjusted according to the capacity
demand and rise to the upper
level every 3 minutes
(When the frequency>COOL_F4
via capacity demand).
COOL_F5 ICOOLLMT1
If the current frequency is lower than COOL_F4, the frequency will
not be limited.
After 10s of the compressor start, if the current>ICOOL, the AC will
display the failure for 30 seconds and stop. The AC will restart 3
minutes later.
Heating mode:
Current Current limit
frequency(Hz) value(A)
HEAT_F16 IHEATLMT12
HEAT_F15 IHEATLMT11
HEAT_F14 IHEATLMT10
HEAT_F13 IHEATLMT9
HEAT_F12 IHEATLMT8
HEAT_F11 IHEATLMT7
HEAT_F10 IHEATLMT6
HEAT_F9 IHEATLMT5
HEAT_F8 IHEATLMT4
HEAT_F7 IHEATLMT3
HEAT_F6 IHEATLMT2
HEAT_F5 IHEATLMT1
If the current frequency is lower than HEAT_F4, the frequency will
not be limited.
After 10s of the compressor start, if the current>IHEAT, the AC will
display the failure for 30 seconds and stop. The AC will restart 3
minutes later.
7.3.7 Indoor / outdoor units communication
protection
If the indoor units cannot receive the feedback
signal from the outdoor units for 2 minutes, the
AC will stop and display the failure.
7.3.8 High condenser coil temp. protection.
When T3>65℃ for 3 seconds, the compressor
will stop while the indoor fan and outdoor fan will
continue.
When T3<52℃, the protection will release and
the compressor will restart after 3 minutes.
7.3.9 Outdoor unit anti-freezing protection
When T2B<0℃ for 250 seconds, the indoor unit
capacity demand will be zero and resume to
normal when T2B>10℃.
7.3.10 Oil return
Running rules:
Frequency limit
Decrease the frequency to
HEAT_F4 and run at HEAT_F4 for
3 minutes.
After that, the frequency will be
adjusted according to the capacity
demand and rise to the upper
level every 3 minutes
(When the frequency>Heat_F4 via
capacity demand).