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Procedure
High pressure switch connection or
pressure sensor connection on outdoor
unit main PCB is loose
Pressure sensor has short‐circuited or
The high pressure side is blocked, caused
by crushed or bent pipe or blocked EXV
The heat exchange is poor
The water flow rate is not sufficient in
Replace outdoor main PCB
Notes:
1.
High pressure switch connection is port CN13 on the main control board of outdoor unit (labeled 10 in Figure 4‐2.2 in Part4, 2.3 "Main PCBs for Refrigerant
System, Inverter Module". Pressure sensor connectin is port CN4 on the main control board of outdoor unit (labeled 15 in Figure 4‐2.2 in Part4, 2.3 "Main
PCBs for Refrigerant System, Inverter Module"
2.
Measure the resistance among the three terminals of the pressure sensor. If the resistance is of the order of mega Ohms or infinite, the pressure sensor
has failed.
3.
High pressure side blockage causes discharge temperature to be higher than normal, discharge pressure to be higher than normal and suction pressure to
be lower than normal.
4.
In heating mode check water side heat exchanger, water piping, circulator pumps and water flow switch for dirt/blockages. In cooling mode check air side
heat exchanger, fan(s) and air outlets for dirt/blockages.
5.
Check water pressure on the manometer. If the water pressure is not > 1 bar, water flow is insufficient. Refer to Figure 2‐1.6 and 2‐1.7 in Part 2, 1.2
"Hydronic Box Layout".
201909 63
P1
1
No
2
failed
No
No
4
No
5
cooling mode
No
Midea CAC Confidential
Ensure the pressure switch is connected
Yes
Yes
Replace the pressure sensor
Yes
Inspect the system and fix the error
3
Yes
Inspect the system and fix the error
Inspect the water system and fix the
Yes
M‐Thermal Split
properly
error
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