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Maintenance Checklists

Complete air conditioning maintenance checklist covering all essential AC system components including safety procedures, filter maintenance, coil cleaning, electrical systems, refrigerant checks, and performance testing for optimal cooling efficiency.

Comprehensive air conditioning maintenance checklist covering safety, filters, coils, electrical systems, refrigerant, and performance testing.

AC Maintenance Checklist 2025: Stay Cool & Reduce Energy Bil

Turn off AC unit and disconnect power (breaker or switch)

Use proper personal protective equipment (gloves, goggles, etc.)

Wait for the unit to cool down before servicing

Ensure ladder or access point is stable and safe

Keep a clear workspace around the unit (remove clutter)

Label wires or take photos before disconnection

Check for signs of pests, insects, or animals inside unit

Use a non-contact voltage tester to verify power is off

Have required tools and cleaning supplies ready

Keep manufacturer's manual and wiring diagrams accessible

Pre-Maintenance & Safety Precautions

Inspect filters for dust, debris, or damage

Clean reusable filters (wash, dry, and reinstall)

Replace disposable filters if clogged or past service life

Check filter frame and housing seals for gaps

Verify correct filter size and orientation

Ensure airflow path (vents, grills) is unobstructed

Check whether airflow seems weak or restricted

Inspect return air grilles for dust buildup

Measure static pressure drop across filter (if instrument available)

Note filter change date and schedule next replacement

Air Filters & Airflow

Inspect the evaporator coil for dirt, mold, or fouling

Clean the coil with suitable coil cleaner / mild detergent

Check the drain pan for standing water or corrosion

Ensure drain trap or P-trap is functioning

Use compressed air or a vacuum to clear clogs

Check for algae, slime, or mold in drain path

Confirm drain slope is adequate toward outlet

Test draining by pouring water and observing flow

Indoor (Evaporator) Coil & Drainage

Clear vegetation, debris, leaves, or obstructions around the unit

Clean condenser coil with water (gentle spray) or coil cleaner

Straighten bent fins on the condenser side

Verify the condenser casing is intact and secured

Check top of unit for foreign objects or nesting material

Ensure sufficient clearance (e.g. 12–24 in) on all sides

Confirm fan guard is secure and undamaged

Inspect condenser fan blades (damage, balance)

Check that the outdoor unit is level and firmly anchored

Outdoor (Condenser) Unit & Coils

Inspect blower fan (indoor) for dust accumulation

Check blower motor mountings and alignment

Lubricate bearings, shafts, and moving parts (if design allows)

Check condition of belts (for belt-driven systems)

Ensure fan blades rotate freely without rubbing

Measure motor amperage draw (compare to nameplate)

Check for unusual noise or vibration during fan operation

Confirm fan speed settings per manufacturer specs

Fans, Motors & Moving Parts

Inspect all electrical wiring and terminations for corrosion or damage

Check contactors, relays, and control switches

Measure voltage and current on motors, compressor, etc.

Inspect capacitors (start, run) and test their microfarad values

Inspect control board or circuit board for signs of overheating

Verify correct operation of safety and limit switches

Inspect fuses, breakers, or overload protection devices

Check and test electrical grounding and bonding

Test wiring insulation resistance (if you have insulation tester)

Electrical & Control Systems

Inspect refrigerant lines and run for damage, corrosion, or insulation degradation

Verify refrigerant charge (pressure test per manufacturer)

Check for leaks (use leak detector or soap solution)

Inspect suction and liquid line insulation

Observe refrigerant line temperatures (superheat / subcooling)

Confirm condenser and evaporator pressures under normal load

Check and service service valves and access ports

Ensure proper spacing and bending radius on pipes

Look for oil stains or residue indicating leaks

Verify that refrigerant matches manufacturer specifications

Refrigerant System & Piping

Calibrate thermostat if possible; compare to actual room temp

Inspect wiring to thermostat for damage or loose terminals

Confirm mode switching (cool, off, auto) functions correctly

Check delay timers / time-off settings / anti-short-cycle features

Ensure thermostat is not exposed to heat sources or sunlight

Verify setpoints are working (e.g. set to cooler, unit engages)

Test zone controls or multiple thermostats if applicable

Record thermostat gain or hysteresis settings

Thermostat & Controls

Inspect ducts for dust, mold, damage, leaks

Seal duct leaks (with mastic or metal tape)

Check insulation on ducts (especially in unconditioned spaces)

Ensure vents / registers are clean and open

Verify that supply and return grills are not blocked

Measure temperature drop between return and supply in each zone

Balance airflow to different rooms (using dampers)

Inspect duct joints and connections for tightness

Clean or vacuum duct interiors if excessive dust

Check for strange odor or moisture in ducts

Ductwork, Vents & Distribution

Run full cooling cycle and observe system behavior

Measure indoor and outdoor temperatures, and ΔT (temperature split)

Record operating pressures and compare to design specs

Monitor for abnormal noise, vibration, or overheating

Confirm that system cycles on and off properly

Check system recovery after power interruption

Document all corrections or parts replaced

Note service date, next scheduled maintenance, and recommendations

Take before/after photos (especially for coils, wiring)

Performance Testing & Documentation

Complete HVAC maintenance checklist covering all essential heating, ventilation, and air conditioning system components including safety procedures, filter maintenance, coil cleaning, refrigerant system checks, electrical controls, and performance testing for optimal system efficiency and longevity.

Comprehensive HVAC maintenance checklist covering safety procedures, air filters, coils, drainage, blowers, refrigerant systems, electrical controls, and performance testing.

HVAC Maintenance Checklist: Prevent Breakdowns & Save Energy

Lock out / tag out power supply (turn off breaker, isolate)

Ensure work area is clean, free of hazards

Wear proper PPE (gloves, safety glasses, etc.)

Check for signs of water, oil, or refrigerant leaks before touching components

Verify presence and operation of CO / gas detectors (if applicable)

Inspect wiring, conduit, junction boxes for damage or exposed conductors

Confirm system is at rest (fans off, compressor off)

Review maintenance history / past logs before starting

Note ambient temperature and humidity as baseline

Safety & Pre-Inspection Checks

Inspect return air filters (check for dirt, clogging, damage)

Confirm filter size and correct orientation (arrow direction)

Check for bypassed filters or unfiltered air return paths

Inspect filter housing and gaskets for sealing integrity

Assess airflow across filters (pressure drop, velocity)

Check for obstructions (curtains, furniture) in front of returns

Confirm that supply registers and grilles are open and unobstructed

Note scheduled filter replacement interval and set reminders

Air Filter & Airflow Management

Inspect evaporator coil for dust, debris, frost, corrosion

Clean evaporator coil using approved cleaner

Check the condenser coil for buildup (leaves, dirt, grime)

Clean condenser coil with water or coil cleaner

Inspect coil fins for damage and straighten bent fins

Ensure proper drain of condensation from coils

Inspect coil insulation (e.g. on suction lines) for deterioration

Check for signs of refrigerant leaks near coil joints

Verify that coil casing and housing are secure and closed

Confirm adequate clearance around outdoor coils (at least 12–24 in)

Coils, Condenser, and Evaporator Components

Inspect condensate drain lines for clogging or blockages

Flush drain lines with water or appropriate chemical (e.g. bleach)

Check primary and secondary drain pans for leaks or corrosion

Verify that pan floats and overflow switches operate correctly

Ensure proper slope on drain piping toward outlet

Inspect trap (U-bend) is intact and full of water

Confirm condensation exits building without backflow

Check for condensation leakage around the system area

Clean and disinfect pans and piping as needed

Condensate Drains & Drainage System

Inspect blower motor, wheel, and housing for dust build-up

Check blower wheel/impeller for damage or imbalance

Verify blower belt condition (cracks, wear) and tension (if belt-driven)

Lubricate blower motor bearings if applicable

Check blower amp draw against rated specification

Inspect supply and return ductwork for leaks, damage, loose joints

Check duct insulation integrity and repair where needed

Verify that dampers and linkages operate and seal properly

Inspect flex ducts for kinks, sagging, or disconnected joints

Blower, Fans & Ductwork

Inspect refrigerant lines for insulation damage, corrosion, or leaks

Check refrigerant charge (pressure/temperature) vs design spec

Verify subcooling / superheat (as appropriate)

Inspect suction and discharge service valves for leaks

Check for oil in sight glass (if applicable)

Confirm proper operation of expansion device (TXV, capillary)

Inspect filter drier or liquid-line filter for restrictions

Check for abnormal vibration or noise in piping

Ensure refrigerant piping is supported and vibration-damped

Record refrigerant type, amounts, and pressures

Refrigerant System / Cooling Cycle

Tighten all electrical connections (terminals, lugs, breakers)

Inspect fuses, circuit breakers, and replace if damaged

Test contactors and relays for proper function

Check capacitors (run, start) with capacitance meter

Measure voltage and amperage on motors (compressor, blower, fan)

Inspect transformer(s) and control circuit wiring

Confirm thermostat wiring and functions (sensors, communications)

Check safety switches, interlocks, and limit devices

Inspect low-voltage controls and wiring insulation

Verify all control logic, and that the system cycles correctly

Inspect burner assembly, flame sensor, igniter, and electrodes

Clean burners and remove soot or carbon deposits

Check heat exchanger for cracks, corrosion, or damage

Test combustion (CO, O₂, CO₂, stack temp) per manufacturer spec

Verify gas pressure and burner gas valve operation

Inspect flue venting, flue pipes, and draft inducer

Check for blockages or corrosion in venting system

Inspect pilot or ignition flame stability

Test safety devices such as limit switch, rollout sensors

Confirm proper startup and shutdown sequences

Heating / Combustion / Heat Exchanger (for systems with heat)

Verify thermostat calibration (compare with independent thermometer)

Test different modes: heating, cooling, auto, fan on/off

Check thermostat placement (avoid direct sunlight, drafts)

Clean thermostat interior (if accessible)

Ensure display, schedule, and programming function properly

Test remote sensors or zone sensors (if present)

Check control sequences, staging, and setpoints

Log any software/firmware version or changes (smart thermostats)

Confirm communication with central control / BMS (if applicable)

Maintenance Checklists

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