Midea MFA-76CRN1, Technical Manual

Page: 119 / 166

R410A Tropical Split Type Technical Manual Troubleshooting
Outdoor Units
119
Low pressure protection
Judge 1: The wiring between the low pressure switch and main
control board is connected well or correctly
Judge 2: Whether the low pressure switch is broken
Connect it well
Validate: Short connect the low pressure switch
socket, check whether the system can run normally
Check whether the refrigerant system is ok
Yes
No
Judge 3: Check whether the outdoor ambient temperature is too low
Yes
Stop the unit
No
Judge 4: The refrigerant of the system is leakage
Yes
Validate: Connect the pressure gauge to the gauge joint of the
system, check whether the pressure is lower than 0.15MPa
Leak hunting: charge nitrogen or
refrigerant to the system, if the
leakage is serious, there will be
distinct gas leakage “cici” sound;
if the leakage is little, use the
suds(mixture of water and
abluent is also ok, if it can make
bubble) or electronic leak
detector.
Judge 5: The refrigerant pipe is blocked
Yes
Drop refrigerant, then use the high
pressure nitrogen or refrigerant to blow
pipe, vacuumize and add the refrigerant
again
No
Replace outdoor PCB
No
No
Yes
Replace low pressure switch