If a home's heat source or air conditioning unit isn't working well, homeowners need an inspection by a heating, ventilating and air conditioning, or HVAC, professional, Bennett says.
The technician will look for problems and likely perform general maintenance on the system, which may include cleaning the burners, tightening connections and checking the system controls, Bennett says.
After the heating and cooling unit is repaired, homeowners still need to budget for regular maintenance on their systems to keep them in good condition, Marston says.
"If the system isn't efficient in the first place, it's probably because the owners didn't keep it properly maintained."
COST: Common problems that HVAC technicians discover -- such as defective igniters and fuses -- are relatively cheap to fix, Bennett says.
"Homeowners can expect to pay a few hundred dollars for these types of repairs," he says.
However, Marston says if the unit is older than 10 years and isn't working properly, it's probably best to buy a new one. Otherwise, even after it's been repaired, it probably won't have the energy efficiency that newer models will have.
New HVAC units cost about $5,000, with high-efficiency models starting at about $10,000, Marston says.