Always Covered. Always Comfortable.TM Always Covered.
Always Comfortable.TM
Trust Frymire for All Your Home Service Needs Trust Frymire for All Your Home
Service Needs


6 Reasons Why Cold Air Is Coming From Your Vents When Your Heater Is On

During the winter season, experiencing cold air coming from your vents is the last thing you want happening when you turn on your heater. Within your AC system you have four main units: your condenser (located outside your home), your coil (located inside your home), your furnace (located inside your home), and your thermostat (located inside your home). The thermostat is probably the unit you are most familiar with as this is what you use to regulate the temperature within your home.

Essentially your AC system does one of two things for you: it is either bringing hot air into your home (heating) or it is taking the hot air out of your home (cooling). Your condenser, coil, furnace, and thermostat work together to make this happen.

With Frymire Home Services, we bring you peace of mind and have listed below six possible reasons why your vent is blowing out cold air instead of hot air.

Why Is Cold Air Coming From My Vents?

It is cold inside your home and you have just turned on your heater. A couple hours go by and you have not noticed any heat changes with the temperature inside your home; it is just as cold, if not colder, as when you turned your heater on. You walk to your thermostat to double-check, and you did turn the heat on! You are puzzled as to why you are experiencing cold air coming through your vents instead of the hot air you are wanting. There are a couple reasons as to why you may be experiencing this issue.

Reason #1

The first reason could be due to the age of your flame sensor. Your flame sensor is located within your furnace and is an important safety feature that not only protects your unit but also protects you. When a flame is ignited within your furnace, your flame sensor makes sure to burn the natural gas to continue the heating cycle. When no flame is detected, your flame sensor automatically shuts off your furnace, ensuring that no natural gas escapes into your unit. As your furnace ages, so does your flame sensor. The only two ways to fix this would be having your flame sensor cleaned or having it replaced.

Reason #2

The second reason could be due to a bad limit switch. Your limit switch is located inside your home and is attached to your furnace. When the heat exchanger becomes too hot, your limit switch acts as a safety mechanism and turns off the burner. Problems arise when your limit switch malfunctions and either continuously runs your blower, never properly ending a heating cycle, or it doesn’t allow your furnace to operate because it is continuously turning off the burner. To fix this you will need to have a technician come out and diagnose the underlying issue. It could be as simple as making sure that your filters and fan blades are cleaned properly or ensuring there is no improper duct sizing or high static pressure. In the end you might have to have your limit switch replaced.

Reason #3

The third reason could be due to a faulty fan or motor. Within your furnace you have your blower fan and your inducer draft motor. Your indoor fan, otherwise known as the “blower,” is responsible for bringing in hot air when in heating mode. The reason this goes out is because the blower has reached the end of its life span, has inadequate ductwork, or has high static pressure. The two ways to fix this are to either lower the static pressure or, if that does not work, replace it with a newer one.

Next, you have your inducer draft motor, which is responsible for removing exhaust gas. The reason this becomes faulty is because it has a restriction or blocked flue pipe, or the windings have burned up. To fix this you need to have the blockage or restrictions cleared, or if that does not work have the motor replaced.

Reason #4

The fourth reason could be due to the age of your gas valve. Your gas valve is located outside your furnace and is what opens and closes the furnace’s fuel system. When you tell your thermostat to heat, your furnace’s gas valves begin to open and close and allow the gas to flow to the pilot light and burner(s). When this stops working properly, the only way this can be fixed is by replacing your gas valve with a newer one.

Reason #5

The fifth reason could be a low refrigerant charge in your AC system, which is due to a leak in either your heat pump or coil. This can be fixed by having a technician locate the leak and repair the leak. If the leak cannot be repaired, you will need to replace your AC system with a newer one. This would only be applicable if you have a heat pump system.

Reason #6

The sixth reason could be due to a bad compressor. The compressor is inside your heat pump, located outside your home. The compressor is the heart of your AC system and is what keeps everything running smoothly. When this goes out you will need to replace it. Some reasons it could go out include that it was over- or under-charged, had a faulty run capacitor, faulty motor, dirty evaporator, or dirty condensing coils, or had undersized ductwork. Again, this is only applicable in heat pump systems.

Frymire Home Services understands the importance of educating and informing our customers and helping them become air conditioning experts! We make sure that we not only correct the issue, but also help the customer understand why the issue happened. To learn more about your air conditioning system visit our website at or call us at 972-913-2881 to schedule an appointment with one of our licensed technicians.

Request Service

Request Service

Ease Comfort Logo Ease Comfort Logo
Always Covered. Always Comfortable.TM with EASE Comfort®

We understand that installing a new heating or air conditioning system can be a significant investment. We help take the stress out of your installation project by offering the EASE Comfort® Program. Through this exclusive program, you’ll enjoy a new, high-efficiency system installation with no money down, no unexpected fees, and a no-hassle maintenance program tailored to your needs.