Here are 3 common issues that may cause your gas furnace to blow cold air:
1) Thermostat is set to ON
Is your furnace blowing cold air only sometimes? Is the furnace blower constantly running?
Check your thermostat, that’s where a tech will start first. If your thermostat fan setting is set to ON, the furnace blower will constantly run even when your furnace isn’t heating the air.
Solution: Turn your thermostat fan setting to AUTO. Now your furnace will only blow warm air.
2) Furnace overheated
Let’s say your furnace blows hot air, then cold air, but then stops blowing any air at all after a while. What’s the problem?
Your filter may be so dirty it’s reducing the air flow. The dirty air filter will block airflow, causing the furnace to run longer to heat your home until it overheats.
It’s possible your furnace overheated. If so, the limit switch, a furnace safety device, turned the furnace burners off. The blower keeps blowing to cool the furnace down to a safe level.
Solution: Change the air filter and see if your furnace starts only blowing warm air.
DON’T ignore this problem. Repeated overheating will hurt the furnace’s heat exchanger, which is expensive to fix.
3) Still blowing cold air?
If your gas furnace is only blowing cold air, then the furnace may need to be reset.
Solution: Turn power off at furnace or the electrical panel for 2 minutes. Turn the system back on. This may help reboot the furnace and solve a minor issue.
Still having problems? Ask one of our experts for help. Have us come out to take a look at your system and take care of it for you.