If a heat pump has been off for more than an hour because of a blown fuse, a tripped circuit breaker, or a utility power failure, the unit should not be operated for about six to eight hours, especially if the temperature is 50 degrees Fahrenheit or lower.
The lubricant in the pump's oil reservoir may be too cool to circulate properly and may cause damage to the valves of the unit. Instead, set the pump on emergency heat. This turns the pump off and keeps it from running.
Leave the pump in this mode for about six to eight hours, then switch the pump to its normal heating setting. If little or no heat is generated at this point, call a professional service person for repairs.
Whatever problem arises with your heat pump at whatever time of the year, you can find solutions in this article.
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