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High Pressure Detected In System; Low Pressure Detected In System - Haier 2U18MS2VHB Service Manual

Ductless multi-split heat pump, outdoor/indoor, wall mount - highwall, 2'x2' compact cassette, 3'x3' large cassette, slim duct, mid-static ducted, medium static ducted, console
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[44] High pressure detected in system

The minimum temperature value of indoor pipe Tm
and outdoor Ts is lower than -45 °C during cooling
mode, or minimum temperature value of outdoor Tc
and outdoor Te is lower than -45 °C.
Possible causes:
• High pressure sensor detection value is incorrect
• Refrigerant overcharge
• Blocked liquid line piping
• The outdoor unit cannot be turned on normally
due to failure to open outdoor heat exchanger
electronic expansion valve when heating.
• The operation environment is beyond the allowed
range.

[45] Low pressure detected in system

The minimum temperature value of indoor pipe Tm and
outdoor Ts is lower than -45 °C during cooling mode, or
minimum temperature value of outdoor Tc and outdoor Te is
lower than -45 °C.
Possible causes:
• Low pressure sensor detection value is incorrect
• Low refrigerant charge
• System air leakage
• Blocked low pressure or liquid line piping
• The outdoor unit cannot be turned on normally due to failure
to open outdoor heat exchanger electronic expansion valve
when heating.
• The operation environment is beyond the allowed range.
Flow Charts
Topic Title
Power off. Is pressure switch
wiring connection ok?
Use multimeter to check the high
pressure switch. Is the switch
short circuited?
Is the EEV coil wiring correct and
firmly in place?
Is the stop valve is open?
Is the piping system is
Is the connection pipe is bent?
Use a multimeter to check
the resistance of Tc & Tm.
Are they withing range?
switch terminal on the PCB.
Is the resistance of Te and
TROUBLESHOOTING & REFERENCES
No
Yes
No
Yes
Yes
No
No
Yes
clogged?
No
No
Yes
No
Power on
Yes
Short the low pressure
Does the system report a
failure?
No
Is the fan motor ok?
Yes
Tc2 in range?
Reconnect
The pressure is bad,
replace it.
No
Reconnect the EEV
coil wiring
Open the stop valve
Clean the piping system
Replace the connection
pipe
Replace the
sensor
Yes
The PCB is bad,
replace it.
No
Replace the fan
motor
No
Replace
sensor
J-27

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