Chicago Furnace Tune-Up Checklist Before Winter

Published: April 12, 2026 · Written by SAVA's EPA-certified HVAC technician with 9 years of Chicago field experience.

Chicago winters regularly see temperatures below 0°F. When your furnace fails in January, you're looking at burst pipes, emergency service calls, and hotel bills. A simple fall tune-up — done in September or October, before you need the heat — can prevent almost all of it. Here's a room-by-room checklist to get your furnace ready before winter hits.

1. Replace the Air Filter

A dirty air filter is the #1 cause of reduced furnace efficiency and overheating. If your filter looks gray and clogged, replace it. Most 1-inch filters should be replaced every 1–3 months during heating season. High-efficiency 4-inch filters can last 6–12 months. When in doubt, replace it — filters are cheap, furnace repairs are not.

2. Check and Test Your Thermostat

Before you need it for real, switch your thermostat from cooling to heating mode and set it 5 degrees above room temperature. Does the furnace start within 1–2 minutes? Does it reach the set temperature? If the furnace doesn't respond, start with fresh batteries. If it still doesn't start, the problem may be the thermostat or the furnace control board.

3. Inspect the Pilot Light or Igniter

On older furnaces with a standing pilot light, the flame should be steady and blue. A yellow or flickering flame can mean incomplete combustion — a safety concern. On modern furnaces with electronic ignition, listen for a clicking sound when the furnace starts. No click, no heat — that's a failed igniter, one of the most common furnace repairs we see in fall.

4. Look for Cracks in the Heat Exchanger (Call a Pro for This One)

The heat exchanger separates combustion gases from your home's air. A cracked heat exchanger can allow carbon monoxide to enter your living space — which is why it's the most serious furnace issue we find during inspections. You cannot reliably inspect a heat exchanger yourself. This is the step to call a technician for.

5. Test Your Carbon Monoxide Detectors

Before heating season starts, press the test button on every CO detector in your home. Replace batteries if needed. CO detectors should be replaced entirely every 5–7 years. If your detector is expired or missing from your furnace room or sleeping areas, replace it before you fire up the heat.

6. Check the Blower Motor and All Vents

Walk through your home and make sure every heating vent is open and unobstructed. Blocked vents cause pressure buildup and reduce efficiency. Then listen to the blower motor when the furnace runs — it should be smooth and quiet. A loud humming or rattling blower is a sign the motor is struggling and may need service.

What a Professional Furnace Tune-Up Includes

When you schedule a professional tune-up with SAVA, the technician performs a 20-point inspection that goes beyond what any homeowner can do safely. This includes:

• Combustion analysis — measuring CO, CO₂, and O₂ levels in the flue gas
• Heat exchanger inspection for cracks (using camera or dye, depending on access)
• Gas pressure and manifold pressure testing
• Measurement of temperature rise across the heat exchanger
• Electrical inspection — checking all contacts, capacitors, and wiring
• Blower wheel cleaning — removes buildup that reduces airflow by 15–25%
• Flue vent inspection for blockages, corrosion, or improper pitch
• Filter replacement (if you supply the filter)

The entire process takes 60–90 minutes on a typical forced-air furnace. At the end, you get a summary of findings and any recommended repairs.

How Much Does a Furnace Tune-Up Cost in Chicago?

Call us for current tune-up pricing. According to the U.S. Department of Energy, regular HVAC maintenance can reduce energy consumption by up to 15%, meaning the tune-up often pays for itself in energy savings over one heating season — and it's far less expensive than an emergency repair call in January during a polar vortex.

Chicago Winters: Why Furnace Maintenance Is More Critical Here

Chicago's climate is more demanding on heating systems than most U.S. cities. The city averages 35 days per year below 20°F, and during polar vortex events — which Illinois has seen in 2019, 2021, and 2024 — temperatures can drop to -20°F or colder. At those temperatures, a furnace isn't just a comfort appliance: it's a life-safety system. A burst pipe from an overnight outage can cause extensive water damage according to insurance industry data.

We serve Chicago and the northwest suburbs year-round. If your furnace hasn't been serviced since 2022 or earlier, schedule a tune-up before October — availability gets tight in November.

Warning Signs Your Furnace Needs More Than a Tune-Up

Some furnace issues go beyond maintenance and require repair:

• Yellow or orange pilot flame (should be blue) — incomplete combustion, possible CO risk
• Furnace cycles on and off frequently without reaching temperature — short cycling
• Burning or metallic smell when the heat runs — overheating or electrical issue
• Gas smell at any time — leave the house and call the gas company immediately
• Soot or black marks around the furnace — sign of combustion problems

Frequently Asked Questions: Furnace Tune-Up

When to Call a Pro

Some of this checklist you can do yourself. But if your furnace doesn't start, makes strange sounds, smells like gas, or hasn't been serviced in over 2 years — call before winter, not during it.

Frequently Asked Questions