Furnace Blowing Cold Air

Professional Furnace Blowing Cold Air in Asheville & Western NC

When your furnace is running but only pushing unheated air through the vents, you have a problem that requires quick action — particularly during WNC's cold mountain winters.

What Causes a Furnace to Blow Cold Air

Several issues can produce this symptom: a worn-out ignitor that fails to light the burners while the blower motor keeps running, a dirty flame sensor that causes the gas valve to shut down seconds after ignition, a tripped high-limit switch from overheating (typically due to a clogged filter), an extinguished pilot light on older standing-pilot units, a thermostat fan setting left on 'on' rather than 'auto', or a cracked heat exchanger that has triggered a safety lockout.

Quick Things You Can Check

Start at the thermostat — confirm it is set to 'heat' with the fan on 'auto' (not 'on'). The 'on' setting runs the blower continuously, circulating unheated air between cycles. Next, inspect the air filter — a badly clogged filter chokes airflow over the heat exchanger, causing it to overheat and trip the limit switch. These two steps resolve the issue roughly 20% of the time.

When This Becomes a Serious Problem

A furnace that lights briefly and then reverts to cold air typically has a failing flame sensor — and repeated ignition failures will eventually lock out the control board. If you detect a gas odor or a CO detector activates, evacuate the home immediately and contact your gas utility. If the furnace is also producing unusual sounds or short cycling, more than one component may be deteriorating.

When to Call for Furnace Repair in Asheville

If adjusting the thermostat and replacing the filter do not solve the problem, professional diagnosis is needed. Quality Mechanical provides 24/7 furnace repair in Asheville — our trucks are stocked with ignitors, flame sensors, and limit switches for same-day no-heat repairs.