Keep your heating and cooling system running efficiently with seasonal filter changes, coil cleaning, ductwork inspection, and professional tune-up scheduling.
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Monthly and Quarterly Tasks
Check and replace the air filter
A dirty filter reduces airflow by 15-25% and forces the system to work harder. Standard 1-inch filters ($3-$8 each) need replacement every 30-60 days. 4-inch pleated filters ($15-$25) last 3-6 months. Hold the old filter up to a light — if you can't see through it, replace it.
Check thermostat operation and battery
Verify the display reads correctly and the system responds to temperature changes. Replace thermostat batteries once per year. Programmable thermostats save 10-15% on heating and cooling when properly set. Keep settings within 5°F of your comfort zone when away.
Clear debris from around the outdoor unit
Maintain 2 feet of clearance around the outdoor condenser on all sides. Remove leaves, grass clippings, and branches. Plants growing against the unit restrict airflow and reduce efficiency by 10-20%. Trim vegetation back quarterly.
Spring Cooling Prep (March-April)
Schedule a professional AC tune-up
A professional tune-up costs $80-$150 and should happen every year before cooling season. The technician checks refrigerant levels, tests electrical connections, cleans coils, and measures airflow. Skipping annual service voids many manufacturer warranties.
Clean the outdoor condenser coils
Spray the coils from inside out with a garden hose at moderate pressure. Remove visible dirt and debris with a soft brush. Bent fins can be straightened with a fin comb ($10-$15). Dirty coils reduce cooling capacity by 20-30%.
Test the AC system before peak heat arrives
Turn the system to cool mode and set the thermostat 5°F below room temperature. The system should start within 1-2 minutes. Check the supply vent temperature — it should be 15-20°F cooler than the return air. If it's not, the system needs service.
Check and clean the condensate drain line
The AC condensate line drains 5-20 gallons of water per day in humid climates. Pour 1 cup of white vinegar down the line every 3 months to prevent algae clogs. A clogged drain line causes water damage in the attic or above the furnace — repairs cost $500-$2,000.
Inspect window seals and weatherstripping
Light a stick of incense near window and door edges — the smoke will dance if air is leaking. Replacing worn weatherstripping ($5-$10 per door) and caulking window gaps saves 10-15% on cooling costs. Focus on south- and west-facing windows.
Fall Heating Prep (September-October)
Schedule a professional furnace tune-up
A furnace tune-up costs $80-$150 and checks the heat exchanger for cracks, tests the igniter, verifies gas pressure, and inspects the flue. A cracked heat exchanger leaks carbon monoxide — this is a life-threatening issue caught during inspection.
Test the heating system before cold weather
Switch to heat mode and set the thermostat 5°F above room temperature. The furnace should fire within 2-3 minutes. A burning dust smell on first use is normal and fades within 30 minutes. If the smell persists or you hear unusual sounds, call a technician.
Replace the air filter with a fresh one
Start the heating season with a new filter. MERV 8-11 filters ($5-$15) trap dust, pollen, and pet dander without restricting airflow. MERV 13+ filters catch finer particles but may reduce airflow in older systems — check your manual first.
Check and clean heat registers and return vents
Remove register covers and vacuum inside the duct opening. Wipe covers with soapy water. Ensure no furniture, rugs, or curtains block vents — blocked vents create pressure imbalances and force the system to work 15-25% harder.
Test carbon monoxide detectors near the furnace
Press the test button on each CO detector. Replace the unit if it's older than 5-7 years. Place a detector within 15 feet of the furnace and on every sleeping level. Gas furnaces, water heaters, and fireplaces all produce CO if malfunctioning.
Seal ductwork joints in accessible areas
Check duct joints in the attic, basement, and crawl space. Seal gaps with foil-faced HVAC tape ($8-$12/roll) or mastic sealant ($10-$15/tub). Leaky ducts lose 20-30% of heated air before it reaches your rooms, wasting $200-$400 per year in energy.
Ductwork and Airflow
Inspect accessible ductwork for damage and disconnections
Look for disconnected joints, crushed flex duct, and holes in the attic and basement. A single disconnected duct joint dumps conditioned air into an unconditioned space. Reconnect with sheet metal screws and seal with HVAC tape.
Check duct insulation for damage
Ducts in unconditioned spaces (attic, crawl space) should have R-6 to R-8 insulation wrap. Torn or missing insulation causes 10-15% energy loss per section. Duct insulation wrap costs $15-$25 per 25-foot roll and installs with HVAC tape.
Verify airflow from all supply vents
Hold a tissue near each supply vent while the system is running. The tissue should flutter from airflow. Weak or no airflow at a single vent may indicate a disconnected or blocked duct. Weak airflow everywhere points to a dirty filter or blower issue.
Consider professional duct cleaning if needed
Professional duct cleaning costs $300-$600 for a whole house. It's worth it if you see visible mold in ducts, rodent droppings, or excessive dust. Cleaning is not needed annually — every 5-7 years is sufficient for most homes. Avoid companies advertising under $100.
System Age and Replacement Planning
Record your system's age and model number
The manufacture date is on the data plate (usually inside the furnace door or on the condenser nameplate). Furnaces last 15-20 years. AC condensers last 12-17 years. Systems older than 15 years should be evaluated for efficiency — modern units use 30-50% less energy.
Track repair costs over the past 2 years
If annual repair costs exceed 50% of a new system's price, replacement is more economical. A new furnace costs $2,500-$5,000 installed. A new AC condenser runs $3,000-$6,000. A combined system replacement is $5,000-$10,000.
Check for available energy efficiency rebates
Federal tax credits cover up to 30% of high-efficiency HVAC equipment costs (up to $2,000 for heat pumps). Utility companies often add $200-$500 in rebates. Check with your utility provider before purchasing — rebates must be applied for in advance with some programs.
Frequently Asked Questions
How often should HVAC systems be professionally serviced?
Schedule professional maintenance twice a year: once in spring for cooling and once in fall for heating. Each service visit costs $75-$200 and includes refrigerant level checks, electrical connection tightening, coil cleaning, and safety testing. Annual service contracts ($150-$300/year) include both visits and typically offer 10-15% discounts on repairs plus priority scheduling during peak seasons.
How often should HVAC air filters be changed?
Standard 1-inch filters need replacement every 30-90 days depending on usage and household factors. Homes with pets, allergies, or heavy dust should change filters every 30 days. Homes without pets in moderate climates can go 90 days. A clogged filter forces the system to work 15% harder, adding $10-$25 per month to energy bills. Higher-rated filters (MERV 11-13) capture more particles but restrict airflow more, so check them monthly.
How long does an HVAC system last?
Air conditioners and heat pumps last 15-20 years, gas furnaces last 20-25 years, and boilers last 25-30 years. Systems in coastal climates with salt air corrode faster and lose 3-5 years of expected life. Well-maintained systems (annual service, regular filter changes) last 20-30% longer than neglected ones. When repair costs exceed 50% of replacement cost, or when the system is over 15 years old and uses R-22 refrigerant (now banned), replacement is the smarter financial choice.
What SEER rating should a new AC have?
The federal minimum SEER rating is 14 for northern states and 15 for southern states (as of 2023). A SEER 16-18 unit costs 15-25% more upfront but saves $100-$300 per year in electricity compared to a SEER 14. The sweet spot for most homeowners is SEER 16, which balances efficiency gains against upfront cost. Units rated SEER 16+ qualify for federal tax credits of up to $2,000 and many utility rebate programs.
How much does it cost to replace an HVAC system?
A new central AC unit costs $3,500-$7,500 installed. A gas furnace runs $2,500-$6,000. A complete system (AC + furnace + coil) costs $6,000-$12,000. A heat pump system costs $4,000-$8,000. Ductwork replacement or modification adds $2,000-$5,000. Most HVAC companies offer financing with 0% interest for 12-18 months. Get 3 quotes and compare equipment brands, warranty terms (look for 10-year parts), and installation guarantees.