Furnace Fan Running Nonstop in Greater Vancouver

A furnace fan that runs continuously — even when the thermostat is not calling for heat — is usually caused by a thermostat setting or a wiring fault, and it is worth diagnosing quickly because it wastes electricity and can cause indoor air to feel uncomfortably dry or drafty.

What This Symptom Means

The blower should run only when the thermostat calls for heat (and briefly afterward to clear residual heat from the exchanger). If it runs all the time, either it has been told to by the thermostat, or a component is keeping the blower relay closed when it should be open.

Common Causes

• Thermostat fan switch set to “On” rather than “Auto”
• Stuck fan relay on the furnace control board keeping the blower energized
• Shorted thermostat wiring between the G terminal and common
• Control board fault causing continuous blower output
• Fan timer not resetting after a heating cycle

What Homeowners Can Check Safely

• Check the thermostat — if the fan switch is set to “On”, change it to “Auto” and see if the fan stops
• Turn the thermostat heat setting below room temperature and wait a few minutes — if the fan continues, the issue is not the thermostat setting

When to Call a Licensed Technician

Some furnace issues require a licensed HVAC technician. Do not attempt to open gas lines, replace internal components, or reset persistent lockouts without professional diagnosis.

• Fan relay inspection and replacement
• Control board diagnosis
• Thermostat wiring inspection for shorts
• Fan limit switch testing

Frequently Asked Questions

Is it okay to run the furnace fan all the time?

Running the fan on "On" intentionally is fine for air circulation and filtration, but it does increase electricity use and filter loading. If the fan is running due to a relay or board fault (not a deliberate thermostat setting), it should be repaired — stuck relays can fail in a way that prevents the blower from shutting off even after the heat exchanger cools, which is a safety concern.

Will a fan running constantly raise my electricity bill?

Yes. A furnace blower motor typically draws 300–700 watts. Running it 24 hours a day instead of the typical 8–12 hours per day during the heating season can add noticeably to your electricity costs. Identifying and fixing the cause is worthwhile.

{“@context”:”https://schema.org”,”@type”:”FAQPage”,”mainEntity”:[{“@type”:”Question”,”name”:”Is it okay to run the furnace fan all the time?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:”Running the fan on “On” intentionally is fine for air circulation and filtration, but it does increase electricity use and filter loading. If the fan is running due to a relay or board fault (not a deliberate thermostat setting), it should be repaired u2014 stuck relays can fail in a way that prevents the blower from shutting off even after the heat exchanger cools, which is a safety concern.”}},{“@type”:”Question”,”name”:”Will a fan running constantly raise my electricity bill?”,”acceptedAnswer”:{“@type”:”Answer”,”text”:”Yes. A furnace blower motor typically draws 300u2013700 watts. Running it 24 hours a day instead of the typical 8u201312 hours per day during the heating season can add noticeably to your electricity costs. Identifying and fixing the cause is worthwhile.”}}]}{“@context”:”https://schema.org”,”@type”:”Article”,”headline”:”Furnace Fan Running Nonstop in Greater Vancouver”,”publisher”:{“@type”:”Organization”,”name”:”HeatLand Heating & Cooling”,”url”:”https://heatland.ca”},”url”:”https://heatland.ca/furnace-fan-running-nonstop-greater-vancouver/”}