Outdoor temperature (ODT)

Outdoor temperature (ODT) is below 75°F, check the following:
i) Perform compressor heating capacity check
ii) If an outdoor thermostat is utilized, check to assure that the setting is at the structure balance point and: If ODT is above the setting of the outdoor thermostat: First stage of indoor thermostat - heat pump only operates. Second stage of indoor thermostat - furnace only operates until second stage is satisfied (this could occur upon heat pump compressor failure) If ODT is below the setting of the outdoor thermostat: First stage of indoor thermostat - furnace only operates (no second stage)
iii) If an outdoor thermostat is not utilized: First stage of indoor thermostat - heat pump only operates. Second stage of indoor thermostat - furnace only operates until second stage is satisfied.