Start by making sure that the furnace thermostat is set correctly. Make sure you are in “heat” mode and that the fan is set to “manual” or “auto.” The temperature should be set between 68° F and 75° F. If the thermostat is set properly, make sure that the filter is not dirty and obstructing the air flow. You should also double check that the breaker on your main electric service panel is in the “on” position. If you have a gas furnace that has an efficiency rating of 90 percent or higher, make sure that the intake and exhaust pipes are not obstructed by leaves, snow, or other debris. Finally, make sure that the front panel of the furnace is fastened securely so that the fan safety switch is in the “on” position.
If the problem appears to be with the heat pump, verify that the thermostat is set correctly and that it is set to “heat pump” mode instead of “emergency heat.” Be sure to check the that the air flow is not blocked due to a dirty filter and that the outdoor portion of the unit is free of leaves and other debris. Check your main electrical panel to make sure that the breaker is in the “on” position. If these measures do not solve the problem, switch the heat pump to “emergency heat” mode and call for service.