You notice the blower is running, but the air from your vents feels cool. In a Longmont winter, that is a frustrating problem, especially when the thermostat says the heat should already be on. The good news is that a furnace blowing cold air often points to a few common issues you can check before scheduling service.
Start With The Thermostat
Check that the thermostat is set to Heat and that the fan is on Auto, not On. If the fan is set to On, it can keep moving air even when the burners are not firing, which makes the house feel like the furnace is blowing cold air. Also check the set temperature. If the thermostat is only a degree or two above the room temperature, the furnace may not call for heat yet.
If the thermostat uses batteries, weak batteries can cause strange behavior. Replacing them is a simple first step that can solve some heating issues.
Check The Furnace Basics
Next, look at the furnace itself. Make sure the power switch near the unit is on. Then check the filter. A clogged filter can restrict airflow and sometimes cause the furnace to overheat and shut down the burners while the fan keeps running. If the filter looks dirty, replace it.
You should also look for the furnace door or access panel. If it is not seated properly, some systems will not operate normally. After a filter change or panel check, give the system a few minutes to cycle and see if warm air returns.
When To Call For Help
If the furnace keeps blowing cool air after those checks, there may be a problem with the ignition system, flame sensor, gas supply, limit switch, or another internal part. Those issues are not something to guess at. If you smell gas, hear unusual noises, or the furnace keeps short cycling, stop using it and get help right away.
Pine Hollow HVAC works with furnace repair in Longmont and nearby Boulder County homes, so if the simple fixes do not solve it, a technician can trace the issue and get the system heating again.
