HVAC emergency in Chicago? Call Bernie's Heating & A/C Service now! Same-day service available for all heating and cooling emergencies.
Cold air does not automatically mean the furnace is dead. We check the simple stuff first, then test ignition, flame sensing, gas, airflow, and safety limits before quoting the repair.
Sometimes the blower is doing exactly what the thermostat asked it to do: fan on, heat off. Other times the burners are failing to light, lighting and dropping out, or shutting down because the furnace overheated.
The symptom feels the same upstairs, but the repair is different. A thermostat setting is free. A dirty flame sensor is usually a small repair. A bad blower motor, gas valve, or cracked heat exchanger is a different conversation.
On many Chicago no-heat calls, we find a furnace that still has power and airflow but no reliable flame. That is why we test the ignition sequence instead of guessing from the vent temperature.
Homeowner check
The blower can run without heat if the fan is set to on instead of auto.
$89-$150 typical
The burners light, then shut off. The blower may keep moving cold air through the ducts.
$150-$250 typical
The furnace starts its sequence but never lights the burners.
$120-$600 depending on cause
Clogged filters, weak blowers, or restricted ducts can overheat the furnace and shut the flame down.
Do these only if the furnace is not making unusual ignition sounds and you do not smell gas.
Set thermostat to heat and fan to auto.
Replace a dirty filter.
Make sure supply and return vents are open.
Check that the furnace switch and breaker are on.
Bungalows and two-flats often have basement ductwork that was changed over the years. Returns get undersized, storage blocks airflow, and old filter slots leak air around the filter.
That makes cold-air complaints tricky. The furnace may need a small ignition repair, but it may also need airflow corrected so the problem does not come back next cold snap.
If this page is close but not exactly your problem, these pages may match what you are seeing.
The blower can run even when burners are off. Common causes include thermostat fan mode, flame sensor failure, a bad ignitor, or a high-limit shutdown from poor airflow.
If it keeps blowing cold air after one reset, turn it off and call for service. Do not keep forcing a gas furnace through failed ignition cycles.
Many cold-air repairs are under $350, especially flame sensor and ignitor problems. Costs rise if the issue is a blower motor, control board, gas valve, or unsafe heat exchanger.
We check thermostat setup, ignition, flame signal, gas, and airflow before recommending parts. No sales script.