High electric bills:

Like the previous complaint, if you are experiencing this problem in the cooling mode during the summer, you should probably call for service. This is mostly a winter-time heating complaint.

Many things can cause high electric bills. This includes a mistake from the electric company, poorly insulated homes, old, inefficient appliances such as electric water heaters and old refrigerators and freezers and just wasting energy.

Ruling these things out usually leaves one culprit - The Heating System, specially if it is a heat pump. The electric bill will be high in the coldest months because that is when the supplemental heat is on the most. But if electric bills are higher than normal it is almost always a sign there could be a problem with the heat pump.

This can range from minor things like a very dirty air filter or an iced-up outdoor unit to severe problems like a damaged compressor.

Below is a list of possible causes.

Outdoor unit not running, using back-up heat
Low refrigerant charge
Refrigerant flow-related problem - restriction/bad metering device
Poor efficiency- needs cleaning and servicing
Bad reversing valve
Bad compressor valves
Compressor not running
Running in A/C mode
Outdoor unit iced-up because of a malfunction
Undersized equipment and/or ductwork
Outdoor unit iced-up - weather related
Snow drift against outdoor unit
Outdoor unit not running, using back-up heat
Dirty air filter
Poorly insulated house, air leaks