From the hallway, a furnace that will not heat looks the same no matter what broke. Inside the cabinet, though, the sequence is strict: inducer on, pressure switch closed, igniter glowing, gas valve open, burners lit, flame proven, and finally the blower sending heat through the house. Most of the diagnosis comes down to finding the broken link. In Tinley Park homes, it tends to be the same handful of culprits: a flame sensor coated in oxide, a hot surface igniter cracked by thermal cycling, a pressure switch held open by a tired inducer or a plugged condensate trap, or a control board with a burned relay.
When the AC quits in summer, see AC Repair.
Warning Signs for Furnace Repair
The sooner you notice these red flags, the easier and cheaper the fix. Here are the most common indicators that it's time to call a professional:
- Frequent on-off cycling that never reaches the thermostat setting
- Yellow, wavering burner flames where they should be sharp blue
- Flames that start, last a few seconds, and go out again and again
- The furnace clicks and glows but the burners never light
- A bang or boom when the burners ignite late
- Squeals, scrapes, or grinding noises behind the blower door
- Air moving through the vents that never gets warm
- Rust streaks, soot, or water around the cabinet or flue
Act Before It Gets Worse
Left unchecked, even a small fault or temperature swing often signals a system working its way toward a breakdown. Call (708) 536-4739 at the first sign of trouble.
