Heat Controller VMH24SC-1, VMH12SC-1, VMH09SC-1, VMH18SC-1 29 P3 Error Low Ambient Protection

Heat Controller, Inc. VMH Series Service Manual

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.

P4:

9.2.10 Inverter compressor drive error diagnosis and solution

Is the connection of compressor good? Is the wiring sequence right? The voltage range proper?

Yes

Replace the outdoor PCB

No

No

Reconnect and retry

Replace inverter compressor.

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.

Check power supply and

connections

Correct power supply or

correct connections

Indoor PCB defective

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