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4.20 Pb Troubleshooting
Digital display output
Description
Water side heat exchanger anti-freeze protection.
M-Thermal Split stops running.
Error code is displayed on hydronic box main PCB and ANTI.FREEZE icon is displayed on user interface.
Possible causes
Normal system protection.
Temperature sensor not connected properly or has malfunctioned.
Hydronic box main PCB damaged.
Procedure
Outdoor ambient temperature is lower
Water side heat exchanger water outlet
temperature sensor, water inlet
temperature sensor or backup electric
heater outlet water temperature sensor
Water side heat exchanger water outlet
temperature sensor, water inlet
temperature sensor or backup electric
heater outlet water temperature sensor
has short-circuited or failed
Replace outdoor main PCB
Notes:
1.
Refer to Part 3, 5.7 "Water Side Heat Exchanger Anti-freeze Protection Control".
2.
Backup electric heater water outlet temperature sensor, water side heat exchanger water inlet temperature sensor and water side heat exchanger water
outlet temperature sensor connections are port CN6 on the hydronic box main PCB (labeled 11 in Figure 4-2.1 in Part4, 2.2 "Main PCB for Hydronic
System").
3.
Measure sensor resistance. If the resistance is too low, the sensor has short-circuited. If the resistance is not consistent with the sensor's resistance
characteristics table, the sensor has failed. Refer to Part 2, 1.2 "Hydronic Box Layout" and to Table 4-5.3 in Part 4, 5.1 "Temperature Sensor Resistance
Characteristics".
201909
Pb
than 4°C
No
2
loose
No
3
No
Midea CAC Confidential
Normal system protection. The system
Yes
will resume automatically
Ensure the temperature sensor is
Yes
connected properly
Yes
Replace the temperature sensor
M-Thermal Split
1
77
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