Why Your Furnace Isn’t Keeping Up in Chicago Winters — And How to Fix It

Chicago winters are some of the harshest in the country, and when temperatures drop into the teens or plunge below zero with windchill, even a well-maintained furnace is pushed to its limits. If your home still feels cold despite the thermostat being set high, it’s typically a sign that something inside your system is struggling.

The long heating season in Chicagoland—often stretching from late October through early April—means furnaces here run longer and more frequently than in most other states. Older homes also tend to have insulation gaps, drafty windows, and airflow imbalances that make it harder to maintain comfortable temperatures. One of the most common reasons a furnace can’t keep up is a clogged air filter. When the filter becomes packed with dust and pet hair, the furnace can’t pull in enough air to heat effectively, leading to weak airflow, cold spots, and a system that runs nonstop without reaching the set temperature. Another frequent culprit is a failing blower motor. If the blower slows down, overheats, or loses power, the heated air never reaches your living spaces with the force it should. In older Chicago homes, heat exchangers can crack from years of heavy usage during extreme cold spells, which can cause the system to short-cycle or shut down entirely. Thermostat issues, duct leaks, or an undersized furnace can also contribute to inadequate heating, especially when temperatures dip below freezing.

Before calling an HVAC technician, there are a few simple troubleshooting steps homeowners can try. Replacing the furnace filter, checking that vents are fully open and unblocked, ensuring thermostat batteries are fresh, resetting tripped breakers, and confirming that the furnace switch is turned on can sometimes resolve minor issues. In Chicago, it’s also important to check outdoor furnace intake and exhaust pipes after snowfalls, since snow or ice can block them and force the system to shut off for safety.

If the furnace is blowing lukewarm or cold air, running nonstop, making unusual scraping or grinding noises, or failing to heat certain rooms, it typically indicates a mechanical issue that requires professional repair. Common repairs include replacing ignitors, sensors, and limit switches, fixing blower motors, sealing ductwork, or, in more serious cases, addressing cracked heat exchangers. Repair costs vary, but in the Chicago area homeowners can generally expect $150–$350 for sensor or ignitor repairs, $300–$900 for blower motor replacements, and $1,200–$2,000 for heat exchanger replacements. Delaying repairs during peak winter months often leads to worsening problems and higher costs, especially since furnaces work their hardest during the coldest nights. If your furnace isn’t keeping up this winter, scheduling an inspection with a trusted

Chicago HVAC technician can restore proper heating, improve efficiency, and prevent emergency breakdowns. Planz Heating & Air offers fast, reliable furnace repair throughout the Chicagoland area to ensure your home stays warm, safe, and comfortable all season long.