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Open High Pressure Switch; Open Low Pressure Switch - 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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[42] Open high pressure switch

High pressure switch: Switch circuit has been detected open for
30 seconds (after 3 minute of compressor run time). Error locks
if it occurs 3 times in 1 hour.
Possible causes:
• Incorrect pressure switch wiring
• Abnormal system pressure
• System is clogged
• Incorrect refrigerant charge
• Bad valve
• Pressure switch is bad
• PCB is bad

[43] Open low pressure switch

Low pressure switch: Switch has been detected open
for 60 seconds (after 3 minute of compressor run
time) or open for 30 seconds during standby.
Possible causes:
• Incorrect pressure switch wiring
• Abnormal system pressure
• System is clogged
• Incorrect refrigerant charge
• Bad valve
• Pressure switch is bad
• PCB is bad
J-26
Flow Charts
Topic Title
switch terminal on the PCB.
Is the resistance of Te and
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 clogged?
Is the connection pipe bent?
Use a multimeter to check
the resistance of Tc & Tm.
Are they withing range?
TROUBLESHOOTING & REFERENCES
Power on
Short the high pressure
Does the system report a
failure?
No
Is the fan motor is ok?
Yes
Tc within range?
No
Yes
No
Yes
No
Yes
No
No
Yes
No
No
Yes
No
Yes
The PCB is bad,
replace it.
No
Replace the fan
motor
No
Replace
sensor
Reconnect
The pressure is bad,
replace it.
Reconnect the EEV
coil wiring
Open the stop valve
Clean the piping system
Replace the connection
pipe
Replace the
sensor

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