10 Reasons Your Furnace Is Blowing Cold Air

Nobody likes Monday mornings. After a long weekend of relaxing and enjoying life outside of work, the early alarm is something most of us wish would go away.

It becomes even worse when you walk into the office and find cold air blowing on you on a cold, blustery winter morning.
Even if your furnace is fairly new, there are still things that can go wrong and cause potential problems. Some are an easy fix and you can have things back to normal in minutes. Others you will be required to call in a professional.
If you walk into your building and face cold air this winter, here are the most common things that may be wrong.
1. A change in the thermostat setting
If you have an office like most, the differences in body temperatures can vary greatly. One employee is too hot, the next is too cold. They bring in sweaters, space heaters, fans – anything to try and control the temperature in their individual spaces. On occasion, an employee will be too hot one day as the sunshine spills into an office, and they will turn the thermostat fan setting from auto to on. With the fan running continuously without providing heat, it can send a cool stream of air into the area. Check the setting – it may be as simple as switching it back to auto.
2. Low batteries
Another common problem is having low batteries. If you can’t remember when you last changed the batteries in your thermostat, trying changing them. Low batteries can prevent temperature changes, leaving the HVAC system in weekend mode.
3. Computer glitches
If you have a newer furnace that uses an electronic control panel, you may have to reset the system. Think of this in the same manner as rebooting your computer when you have glitches to the system. A fresh reboot may reconnect and start the system running again.
4. Pilot light
If you have an older furnace, the pilot light may have gone out. This can happen for a variety of reasons, from a gust of wind to unexpected activity near the furnace. If you are comfortable, you can try relighting the pilot light yourself.
5. Dirty filter
When was the last time you changed the air filter? Dirty air filters can impact furnaces in a variety of ways, including turning off the burner when the system is overloaded. Try changing the air filter and rebooting the system.
6. Faulty valve
If the pilot light won’t light, you may have a problem with the gas valve. If you haven’t cleaned or maintained the system in a while, dirt and debris can accumulate. Have a HVAC professional completely clean and check your system to find the underlying cause.
7. Faulty ignition
If you have a newer furnace with an electronic ignition, the system may need adjustment. This problem requires maintenance from a HVAC professional, and can easily be found and repaired.
8. Leaking ducts
Your HVAC system has many components to make the system work efficiently, including the duct work. As it ages, holes and cracks may form especially around the joints. If hot air escapes, it can impact the entire building’s temperature, giving false readings back in the control panel.
9. Oil filter
If you have an oil fired furnace, the oil filter could be your problem. Just like an air filter can clog with dirt and debris on a gas fired system, the same can happen with an oil filter on an oil fired furnace. While you can clean or replace the filter yourself, it is a messy job, one that is part of routine maintenance when you hire a professional.
10. Flame sensor
Do you occasionally find your vents blowing warm air, yet it quickly turns to cold? That kind of behavior can make you question if a problem truly exists. In many cases, this stems from a faulty flame sensor. If the flame sensor is covered with grime or simply worn out, it can cause the burner to shut off before its completed the process. Cleaning or replacing it will bring the system back into working order.


Have additional questions about your HVAC system? Give us a call today. We would be happy to answer any questions you may have, and help you determine the next step in making your building’s heating and cooling needs more efficient.

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