AC repair costs $150 to $650 on average, depending on the issue and the AC unit's age and warranty status. Major air conditioner repairs cost $650 to $2,500+ if the unit is out of warranty.

Common AC repairs and maintenance services include:

• Evaporator coil cleaning or replacement
• AC leak repair
• Compressor replacement
• Capacitor replacement
• Condenser replacement
• Drain line flushing

Air conditioning companies typically don't give free estimates for repairs. A service call for a heating and cooling system costs $75 to $200 to diagnose the problem.

Central heating and cooling replacement costs $5,000 to $11,000, including a new furnace and central AC unit. Total costs depend on the house size and the HVAC system size, type, SEER rating, and brand. Installing a new system with new ductwork costs $7,000 to $16,000 on average.

• AC units with a higher Seasonal Energy Efficiency Ratio (SEER) rating cost the most up front but are more efficient and reduce your energy costs.
• Central air conditioning systems from popular brands like Carrier, Trane, and Lennox typically cost more than units from Armstrong, Goodman, or Bryant.

Installing optional features like an HVAC zoning system or new smart thermostat will increase your total upfront costs but may reduce energy costs in the long-term.

Heating and cooling companies typically offer these services:

• AC / HVAC installation
• Air conditioning repair and replacement
• Ductless mini-split AC installation and repair
• Seasonal air conditioning and heater maintenance
• Refrigerant recharge / refill
• Ductwork installation and replacement
• Thermostat repair and replacement
• HVAC zoning system installation
• Furnace repair and replacement
• Heat pump repair and replacement
• Boiler repair and replacement

Installing new central air conditioning increases a home's resale value by 2% to 10%, depending on your location. Central air is a good investment in warm climates but provides less value in regions with mild summer weather.

Replacing an existing central air system maintains but doesn't increase the home's value. However, upgrading to a more efficient system with a higher SEER rating may appeal to home buyers.

Look for these signs your HVAC system needs repairs or replacing:

• Increase in energy bills
• Weak or limited airflow from the vents
• Uneven home heating or cooling
• AC unit or furnace cycles on and off frequently
• Furnace ignition difficulties or failure to switch on
• Loud knocking, clicking, or gurgling noises from the system
• Abnormal or musty odors from the system
• Dust or soot accumulation
• Debris coming from the vents

Installing or replacing a central AC or HVAC system takes 1 to 2 days if using the existing ductwork or 3 to 5+ days if replacing old ductwork.

Contact an AC repair company immediately if your air conditioner is leaking refrigerant. Inhaling refrigerant gas can be fatal.

It's normal for an AC unit to leak a small amount of water due to condensation. Flush the drain line monthly with a 50/50 mix of distilled white vinegar and warm water to prevent blockages that could cause the drain pan to overflow.

Follow these tips when hiring an HVAC company near you:

• Get at least three estimates with equipment of the same size and quality to compare.
• Look for a NATE-certified company.
• Select an HVAC contractor who will perform a complete home evaluation to assess your heating and cooling needs.
• Read reviews and check out their previous work on HomeGuide and Google.
• Select companies that are insured, bonded, and have been in business for 5+ years.
• Get a detailed estimate, contract, and warranty in writing before the work begins.
• Never pay in full before the project starts.

Ask these questions to help you find the best HVAC company near you:

• How long have you been in business?
• Are you NATE-certified?
• Are you licensed, bonded, and insured?
• Do you charge a fee to diagnose the problem?
• Can my air conditioner be repaired or does it need replacing?
• Do the new parts come with a warranty?
• Do you warranty the labor?
• Do you offer any seasonal discounts or promotions?
• How much is an HVAC maintenance plan, and what does it include?