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Heat Controller, Inc. VMH SERIES Service Manual
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9.29 P3 ERROR – Low Ambient Protection
If the outdoor temperature remains at 5°F(-15°C) for an hour, the compressor will turn off and the error
code “P3” will be displayed on the indoor unit. Once the compressor has been off for at least an hour and
the temperature outside is equal to or greater than 10.4°F(-12°C) for at least ten minutes, the system will
restart. Additionally if the outside temperature reaches at least 41°F(5°C) for at least ten minutes, the
system will restart without the needed 1 hour compressor off time required.
9.2.10 Inverter compressor drive error diagnosis and solution
9.2.9 Zero crossing check resistance or inverter compressor, it is .7Ω error
Alarm signal when the main chip can’t detect over-zero signal. When such failure occurs, the main control
board must have fault.
Yes
Replace the outdoor PCB
Replace inverter compressor.
Reconnect and retry
No
No
Is the connection of compressor good?
Is the wiring sequence right? The voltage
range proper?
P4:
Check power supply and
connections
Indoor PCB defective
Correct power supply or
correct connections