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Central Air Conditioning Maintenance Guide

An HVAC technician servicing an air conditioning unit with precision tools.
An HVAC technician servicing an air conditioning unit with precision tools.

A building’s central air-conditioning system requires regular inspection and maintenance. While professional annual inspections are recommended, homeowners can perform many maintenance tasks themselves.

Clean the Exterior Condenser Unit

Before Starting:

  • Turn off power to the unit

Steps:

  1. Remove debris (leaves, spider webs) from unit exterior
  2. Trim foliage back several feet for proper airflow
  3. Remove cover grille and clean interior (garden hose recommended)
  4. Straighten bent fins using a fin comb
  5. Add lubricating oil to motor (follow manual instructions)
  6. Clean evaporator and condenser coils annually
Cleaning the AC unit with a microfiber glove for a fresh and cool environment.
Cleaning the AC unit with a microfiber glove for a fresh and cool environment.

Inspect the Condensate Drain Line

Location: Side of inside fan unit

Key Tasks:

  • Check for obstructions (algae, debris)
  • Verify hoses are secure and properly fitted
  • Monitor both primary and secondary drain lines (if present)

Warning: Blocked lines can cause water damage and safety hazards

Rusty HVAC condensate drain pipes emptying into a basement floor drain.
Rusty HVAC condensate drain pipes emptying into a basement floor drain.

Clean the Air Filter

Specifications:

  • Typically 20″ x 16″ x 1″
  • Located in main ductwork near inside fan unit

Maintenance Schedule:

  • Replace monthly during cooling seasons
  • More frequent changes needed for:
    • Constant AC use
    • Occupants with respiratory problems
    • Homes with pets
    • Dusty conditions

Benefits:

  • Improves indoor air quality
  • Reduces motor strain
  • Increases energy efficiency
  • Lowers energy costs
Out with the old, in with the clean—swapping dirty HVAC filters for fresh air and efficiency.
Out with the old, in with the clean—swapping dirty HVAC filters for fresh air and efficiency.

Seasonal Maintenance & Other Recommendations

Cover Exterior Unit (Winter):

  • Purchase cover or make one from plastic trash bags
  • Prevents ice, leaves, and dirt damage
  • Turn unit off before covering

Air-Distribution Registers:

  • Close after cooling season
  • Prevents warm air back-flow
  • Blocks pests and dust
  • Remember to reopen before cooling season
  • Ensure no blockage by furniture, drapes, or carpeting

Other Recommendations:

  • Schedule professional inspection annually before cooling season
  • Enhance home energy efficiency:
    • Switch to compact fluorescent lights
    • Reduce heat-producing elements
A backyard air conditioning unit wrapped for winter protection, surrounded by fallen autumn leaves.
A backyard air conditioning unit wrapped for winter protection, surrounded by fallen autumn leaves.

Summary: Maintaining the Air Conditioning Unit

Fallen autumn leaves rest on a mesh-covered outdoor AC unit.
Fallen autumn leaves rest on a mesh-covered outdoor AC unit.

Regular maintenance of central air conditioning systems can be performed by homeowners through:

  • Regular cleaning of external units
  • Drain line inspection
  • Air filter maintenance
  • Seasonal preparation
  • Professional annual inspections

These steps help ensure efficient operation, prevent damage, and extend system life.