HVAC Maintenance Checklist: What Homeowners Should Do Each Season

Your HVAC system needs attention four times a year, plus a quick monthly check. Here’s a seasonal checklist you can follow yourself, with notes on what’s worth calling a tech for.

Monthly: Change or Check the Filter

This is the one most homeowners skip. A clogged filter starves your system of airflow, which makes the blower work harder, raises your energy bill, and can freeze up a coil in summer or cause the heat exchanger to overheat in winter.

Pull the filter out and hold it up to a light. If you can’t see light through it, swap it. In dusty Bay Area conditions (wildfire season, construction nearby), you may need to change it every 3-4 weeks instead of the usual 1-3 months. Keep a couple of spares in the garage so there’s no excuse.

Spring (Before You Turn on the AC)

A few things to do in April or early May, before the first hot weekend:

Clear the outdoor condenser. Over winter, debris collects around it. Turn off power at the disconnect box first, then clear any leaves, dirt, or overgrown plants from the sides and top. Most manufacturers call for at least 2 feet of clearance on all sides; check your unit’s label or manual for the exact number.

Inspect the fins. Those thin metal fins on the outside of the condenser can get bent and block airflow. A fin comb (cheap, hardware stores carry them) straightens them out. Don’t use a pressure washer; it bends the fins worse.

Check the condensate drain line. The AC pulls humidity out of the air and that water drains out through a PVC line, usually to a floor drain or outside. If it’s clogged, you’ll get a puddle near the air handler. Pour about a cup of white vinegar down the access point every spring to keep algae from building up. (Avoid bleach; it can be corrosive to the drain line and coil materials.)

Turn it on and listen. Run a short test cycle. You’re listening for unusual rattling, clanking, or grinding. The system should reach set temperature within a reasonable time. If it’s running a long time and not cooling, low refrigerant is one possibility, and that requires a licensed tech with proper equipment.

Fall (Before the Heat Comes On)

Do this in September or October before you actually need it:

Replace the filter (yes, again).

Test the furnace or heat pump early. Switch to heat and run it for a few minutes. A brief burning smell the first time is usually just dust burning off. Smoke, persistent odors, or no heat at all means stop and call someone.

Inspect the flue and venting. On gas furnaces, the exhaust flue needs to be intact, properly sloped, and free of nests or blockages. Visually follow the vent pipe from the furnace to where it exits the house. Any cracks, disconnected sections, or visible rust are worth having a pro look at, since a damaged flue can put carbon monoxide into living space.

Test your carbon monoxide detectors. Not an HVAC task exactly, but relevant. Do it every fall when you service the furnace.

Clear the area around the furnace. Don’t store boxes or combustibles within a few feet of the unit.

Annual Professional Tune-Up

Once a year, ideally before summer for the AC side and before fall for the heating side, a tech should do a more thorough inspection. What that typically covers:

• Checking refrigerant charge and looking for leaks (requires EPA Section 608 certification, not a DIY task)
• Measuring electrical draw on the blower motor and compressor
• Inspecting the heat exchanger for cracks (critical on gas furnaces, since a cracked exchanger can allow carbon monoxide into living space)
• Cleaning the evaporator coil if accessible
• Verifying the thermostat is calibrated correctly
• Checking capacitors (these degrade over time and a weak capacitor is one of the more common reasons systems don’t start up in summer)

Not every company inspects every item on this list, so it’s worth asking what’s included before you book.

Heat Pumps: A Few Extra Notes

If you have a heat pump instead of a separate furnace and AC, most of the same steps apply. One difference: heat pumps run year-round, so outdoor unit clearance and filter changes matter in winter too, not just summer. Also, heat pumps in heating mode will occasionally go through a defrost cycle where the outdoor unit looks like it’s steaming and the indoor unit blows cooler air for up to about 15 minutes. That’s normal. If it’s running in defrost constantly or not heating at all when it’s cold, that’s a service call.

When to Call a Pro

Call a tech (don’t DIY) for these:

• Refrigerant issues. Handling refrigerant requires EPA Section 608 certification. If your system is low on refrigerant, it also has a leak somewhere that needs to be found and fixed.
• Gas furnace concerns. Anything involving the burner, heat exchanger, or flue.
• Electrical problems inside the unit.
• The system isn’t reaching temperature despite a clean filter and clear outdoor unit.
• Any smell of burning electrical components or gas.

For Bay Area homeowners, the good news is that our climate is mild enough that most systems run less hard than they would in Phoenix or Chicago. That said, systems that sit idle for months can surprise you with a failure right when you need them. A spring check in April and a fall check in October keeps things predictable.

If you want a tech to handle the annual tune-up or you run into something that needs a professional, bayareahvacservice.com covers the East Bay, South Bay, and surrounding areas.

Key takeaways

• Change or inspect your filter every 1-4 weeks depending on conditions, not just once a year.
• Spring AC prep and fall furnace prep each take under an hour and can prevent expensive mid-season failures.
• Refrigerant, gas furnace internals, and electrical faults inside the unit are not DIY tasks.
• A pro tune-up once a year catches things like weak capacitors, refrigerant leaks, and cracked heat exchangers before they cause a breakdown.

Related questions

Written by Andrew Kuznetsov. Andrew is the founder and owner of Bay Area HVAC Service (ADRIUM Service Solutions). He holds a California Contractor License (CSLB #1136642), EPA 608 certification, and completed factory training at the Daikin/Goodman plant in Houston in 2025. He writes from direct field experience, not marketing copy.

Further reading

• Mitsubishi Hyper-Heat (H2i): How It Keeps Putting Out Heat When It Gets Cold in the Bay Area , Most people think heat pumps quit when it gets cold. Mitsubishi's Hyper-Heat (H2i) line is built to keep working as temperatures drop, which matters more here than folks expect, especially on cold mornings and up in the East Bay hills.
• Mitsubishi Mini-Split Blinking a Fault Light? What It Means and What to Do , A blinking light on your Mitsubishi indoor head is the system telling you something is wrong. Here is what the blink pattern means, the checks you can safely do yourself, and when to bring in a factory-trained tech.
• Why Your Mitsubishi Mini-Split Is Leaking Water Inside (and How to Fix It) , A Mitsubishi mini-split dripping water inside almost always comes down to condensate that can't drain. Here's what causes it, the safe checks you can do yourself, and when to call a tech.