Posting Date: October 17, 2017
Posted by: Rusty Herd, Branch Manager of Georgetown, TX
If your gas furnace is blowing cool air, it could be a simple fix – or a complicated repair. Here are three common causes for cool air coming from your furnace that you can fix yourself.
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Your thermostat is set to ON – If your furnace is blowing cold air only some times – even though the blow is constantly running – the problem could be your thermostat. If your thermostat’s fan setting is set to ON, the blower will run even when your furnace isn’t heating the air.
- Solution: Set your thermostat fan to “AUTO” rather than “ON.”
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Your furnace has overheated – If your furnace has stopped blowing warm air after consistently blowing hot air, it could be overheated (your furnace has a “limit switch” – a safety device that turns the furnace burners off; the blower keeps operating to cool the furnace).
What causes the furnace to overheat? More often than not, a dirty furnace air filter is the culprit. By blocking airflow, the clogged air filter causes the furnace to overwork to heat your home.
- Solution: Change the air filter and see if your furnace starts operating properly again. DON’T IGNORE THE PROBLEM! Repeated overheating can damage the furnace’s heat exchanger, which is expensive to fix.
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Your pilot light is out – If your gas furnace is only blowing cold air, it could be because your pilot light may be out. Check to see if it is and try these solutions:
- Solution 1: If you’re comfortable with doing so, re-ignite your pilot light, following the manufacturer’s instructions carefully. If you’re not, don’t worry – just contact us.
- Solution 2: If the pilot won’t light, make sure the furnace’s gas valve switch is in the “on” position (parallel/in line with the gas supply pipe).
- Solution 3: If the pilot lights but won’t stay lit, your thermocouple (the copper rod you see contacting the pilot flame) needs to be adjusted or replaced – a job for professional technician.
Still having problems? Ask one of our experts! Give us more details about your problem, and we’ll get back to you ASAP.