A standard HVAC maintenance checklist has two columns: things you can knock out in an afternoon, and things that actually require a licensed tech. Most homeowners mix them up. Here’s how to split them clearly, so you go into each season without surprises.
Change or Check the Air Filter First
This is the one task every homeowner should own completely. A clogged filter chokes airflow, makes the system work harder, and can cause the evaporator coil to freeze over in summer or overheat the heat exchanger in winter.
Pull the filter out. Hold it up to a light. If you can’t see light through it, it’s done. Replace it. Most homes do fine with a 1-inch filter changed every 60-90 days, but if you have pets or dusty conditions, check it monthly. Write the date on the frame with a marker.
Stick with MERV 8 to MERV 11 for most residential systems. Higher MERV ratings trap more particles but restrict airflow more, and not every system can handle that. If you’re unsure, match what was in there originally.
Clear the Area Around the Outdoor Unit
Before summer cooling season, walk out to the condenser. Give it a look.
- Trim back any shrubs or overgrowth to maintain the clearance specified in your unit’s installation manual — typically at least 12 inches on the sides, though many manufacturers call for more. When in doubt, give it two feet.
- Remove leaves, seed pods, or debris from the top and sides of the cabinet.
- Gently rinse the fins with a garden hose from the inside out if you can access them, or just from the outside on a low setting. Don’t use a pressure washer.
In fall, if you’re heading into a heating-only period, clear the area again. Some people cover the condenser for winter. That’s fine for debris, but don’t use a full cover that seals it airtight — you need airflow if the heat pump runs in mild weather.
Test the System Before the Season Starts
Don’t wait until the first hot day in June to find out the AC doesn’t work. Run it in early spring when temps are still mild. Turn it on, let it run for 10-15 minutes, and check that cool air is actually coming from the vents. Same in fall: run the heat before you actually need it.
If the system short-cycles (turns on and off every few minutes), blows warm air in cooling mode, or makes a noise it didn’t make before, that’s your cue to call.
Check Vents and Registers
Walk through the house and look at every supply and return vent. Make sure none are blocked by furniture, rugs, or curtains. Blocked vents throw off the balance of the system and create hot or cold spots.
Remove the vent covers if you can and vacuum out any visible dust buildup in the first foot or so of the duct. That’s straightforward homeowner territory.
Inspect the Condensate Drain Line
The condensate drain is a PVC pipe (usually 3/4 inch) that runs from the air handler to a floor drain or outside. In summer, it removes the moisture your AC pulls from the air. When it clogs with algae or debris, the drain pan overflows and you get water damage.
You can flush it yourself: find the clean-out cap near the air handler and pour a small amount of diluted bleach or distilled white vinegar into it during cooling season to discourage algae buildup. Check your air handler’s manual first — some manufacturers specifically recommend vinegar over bleach to avoid degrading seals and pipe joints. If the manual doesn’t say, diluted white vinegar is the safer default.
If the drain is already clogged and the pan has standing water, that’s still DIY territory — you can use a wet/dry vac on the drain outlet — but if you’re not sure where the outlet is or the pan keeps filling back up, a tech should check it.
What You Should Leave to a Licensed Tech
There’s a clear line between cleaning and maintenance versus working on refrigerant, electrical, or combustion components. Don’t cross it.
Refrigerant check and recharge. If the system isn’t cooling well, low refrigerant is a possible cause. But only an EPA-certified tech can legally handle refrigerants under Section 608 of the Clean Air Act. More importantly, low refrigerant means there’s a leak somewhere. Adding refrigerant without finding and fixing the leak is wasted money. A tech will check pressures, find the leak, repair it, and charge the system to spec.
Electrical inspection. The capacitors, contactors, and wiring inside the outdoor unit carry line voltage. Capacitors hold a charge even when the power is off. Inspecting and testing these components is tech work.
Combustion check on gas furnaces. If you have a gas furnace, the heat exchanger, burners, and flue need to be inspected annually. A cracked heat exchanger can allow combustion gases including carbon monoxide to enter the living space. You can’t reliably detect a crack with a visual check from the front panel. A tech inspects the exchanger under operating conditions with proper instruments.
Coil cleaning. The evaporator coil (inside) collects dust and eventually needs a chemical cleaning. You can’t access it without opening the air handler. A tech does this as part of a full tune-up.
Blower motor check. If your air handler has a belt-drive blower (found on older systems), belt tension and motor amperage should be checked by a tech. Direct-drive motors are standard on most systems installed in the last couple of decades, but bearing wear shows up in amperage readings before it becomes audible noise.
When to Call Before the Season, Not After
A pre-season tune-up, usually called a maintenance visit, typically covers the things listed above plus a full electrical and refrigerant check. Scheduling one in early spring (before the first heat wave) or early fall (before the first cold snap) means you’re not competing for appointments with everyone else whose system just failed.
If your system is more than 10 years old and hasn’t been serviced in a while, I’d prioritize the gas furnace inspection above everything else. Heat exchanger integrity isn’t something to guess at.
For anything beyond the filter, drain line, and basic cleaning, we handle HVAC maintenance across Tri-Valley and the East Bay. You can book at adriumservice.com or call to ask whether what you’re seeing actually warrants a visit.