DIY Furnace Cleaning: What You Can and Can’t Do Safely

Make it a habit to spend a few minutes each month in your mechanical room. During the heating season, remove the front cover of your furnace for a quick visual inspection. You’re not doing repairs — just checking for anything unusual.

The first thing to look for is water staining or rust.

• • Bottom of the furnace: Rust stains often mean the condensate trap has been leaking. If you’re handy, you might tighten a few clamps to stop minor drips.

  • Middle section: Check for any signs of water or rust where there shouldn’t be. Furnaces are not designed to hold water, so moisture is always a red flag.

Once rust appears, it’s difficult to remove — so catching leaks early is key.

Next, check for burn marks. You should never see any scorch marks on your furnace. If you do, stop immediately and call a professional HVAC technician.

Listen to your furnace motor while it’s running. A high-pitched squeal or whining noise could mean your inducer fan is wearing out. Early detection helps prevent sudden breakdowns.

When you remove the furnace cover, you’ll notice a door switch that automatically shuts off power to the system. That means you can’t run the furnace while the cover is off — and you shouldn’t try to override it.

Check that your furnace filter hasn’t been sucked into the fan, and that there’s no water pooling at the bottom. Replace or clean your filter regularly to maintain proper airflow.

Before scheduling service, take a photo of your furnace’s model and serial number. This helps your technician prepare for your specific system and can save time (and cost) if replacement parts are needed.

By performing safe visual checks and leaving the technical work to professionals, you’ll protect your system and avoid costly mistakes.