Midea SMK-60/CGN8, Service Manual

Page: 71 / 86

M‐Thermal Split
70 201909
Midea M‐Thermal Split Ser
vice Manual
Procedure
P5
Water side heat exchanger water inlet /
outlet temperature sensor is loose
1
Yes
Ensure the temperature sensor is
connected properly
No
Water side heat exchanger water inlet /
outlet temperature sensor has
short‐circuited or failed
2
Yes
Replace the temperature sensor
No
Water piping contains air
Yes
Purge air from the water system
2
No
The water flow rate is not sufficient,
caused by crushed or bent water piping,
incorrect pump speed setting, high
resistance in water piping or broken
expansion vessel
4
Yes
Inspect the system and fix the error
No
Replace hydronic box main PCB
Notes:
1. 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 (labeled11 in Figure 4‐2.1 in Part4, 2.2 "Main PCB for Hydronic System").
2. 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 5‐5.3 in Part 5, 5.1 “Temperature Sensor Resistance
Characteristics”.
3. Refer to the M‐Thermal Split Engineering Data Book, Part 5, 15 “SPECIAL FUNCTIONS”.
4. Check water pressure on the manometer. If the water pressure is not > 1 bar, water flow is insufficient. Refer to Figures 2‐1.7 and 2‐1.8 in Part 2, 1.2
“Hydronic Box Layout”.
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