Low Pressure Protection (Odu P2) - Heat Controller A-VMH18DC-1 Service Manual

Heat Controller, Inc.
9.3.2.7 Low pressure protection (ODU P2) (Only for A-VMH36QC-1)
Low pressure protection
Is the wiring between the
low pressure protector
and main control board
connected correctly?
Is the low pressure
protector broken?
Short circuit the low
pressure protector socket,
check whether the system
can run normally now?
Check whether the
temperature is to low
a refrigerant leak
Connect the pressure gauge to
the gauge joint of the system,
check whether the pressure is
lower than 0.14MPa
Check whether the
refrigerant circuit is
Replace outdoor main board
Yes
Yes
No
Check whether
the refrigerant
system is ok
outdoor ambient
No
Check if there is
Yes
No
blocked or not
No
VMH SerieS
No Reconnect it properly
Yes Replace low pressure protector
Yes Stop the unit
Find the leak by charging nitrogen or refrigerant
into the system, if the leak is serious there will be
distinct "hissing" sound; if the leakage is small, use a
soap and water mixture or electronic leak detector
to find the leak and repair.
Evacuate the refrigerant, then use
high pressure nitrogen or refrigerant
Yes
to blow out pipe, vacuum and
recharge with refrigerant again
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Service Manual