Google Nest · Thermostat error code

E55 / E105Overcurrent on O/B

Single source High-voltage / caution

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

Related diagnostic guides

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Heat pump blows cold on heat (or warm on cool): O/B setting

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4 steps ~20 mineasy

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