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Furnace Blower Running Constantly
in Columbus, GA
The blower in your furnace should run during a heating cycle and then stop. If it keeps running all day and night, the system is wasting electricity and the motor will wear out faster than it should. Columbus homes deal with heavy pollen loads in spring and fall that clog filters, and a clogged filter makes the furnace run hotter than designed.
Quick Answer
A furnace blower that never stops usually means the fan limit switch is set wrong or has failed, or the thermostat fan setting is stuck on. In Columbus, dirty filters from our pine pollen seasons push this problem along by overheating the unit. Call (762) 275-8579 to get the switch tested before your blower motor burns out.
Telltale Signs
Warning Signs to Watch For
- The fan runs continuously even when the thermostat is not calling for heat
- Your electric bill jumps noticeably in winter without a clear reason
- Warm air blows for a while, then the air turns cold but the fan keeps going
- The thermostat fan switch is set to auto but the fan ignores it
- You hear the blower running at 2 a.m. when the house is already at the set temperature
Root Causes
What Causes Furnace Blower Running Constantly?
Failed Fan Limit Switch
The fan limit switch tells the blower when to start and stop based on furnace temperature. When it fails in the closed position, it keeps sending power to the blower regardless of what the thermostat says. This is common on furnaces that have overheated repeatedly due to restricted airflow.
The Fix
Fan Limit Switch Replacement
The old switch is pulled and a matching replacement is wired in. The technician also checks why the furnace overheated in the first place so the new switch does not fail the same way.
Thermostat Wiring or Setting Problem
Some older Columbus homes, especially those built in the Wynnton area in the 1960s and 1970s, have thermostats with a manual fan switch that gets bumped to the on position. A wiring fault in older thermostat cable can also send a constant fan signal.
The Fix
Thermostat Inspection and Repair
A technician checks the thermostat wiring at both ends and confirms the fan control is working correctly. In many cases a thermostat replacement solves it for good.
Self-Diagnosis
Which Cause Applies to You?
Check the signs you're observing to narrow down the likely root cause before your inspection.
| What You're Seeing | Failed Fan Limit Switch | Thermostat Wiring or Setting Problem |
|---|---|---|
| Fan runs nonstop even with thermostat set to off | ||
| Fan switch on thermostat is confirmed set to auto but fan ignores it | ||
| Blower stops when you manually flip thermostat fan switch to off | ||
| Furnace has a history of overheating or tripping high-limit safety |
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An on-site inspection is the only way to confirm which cause applies to your property. Free, no obligation.
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