Why is My Furnace Blowing Cold Air?
With the frigid winters in the Chicago area, the job of your furnace is a critical one, keeping your family warm and your home protected from the cold. When your furnace is blowing cold air, it is easy to think that there is something seriously wrong, but that is not always the case.
When Cold Air from the Furnace Is Normal
Cold air is possible during normal furnace operation. When the furnace first starts after being off for a while, there will be cool air in the ductwork. Once the furnace blower starts pushing warm air into the ducts, this cooler air will be expelled into your home. This should only last for a minute or two before the heated air arrives. In some cases, it may take longer, such as when a damaged fan limiter starts the blower immediately, instead of waiting for the heat exchanger to reach the proper temperature before turning the blower on.
Problems that Can Cause Your Chicago Furnace to Blow Cold Air
When your furnace continues to blow cold air long after the startup period, there may indeed be something wrong, though it could be as minor as incorrect settings on the thermostat.
Here are some of the most common causes of cold air from your furnace:
Incorrect Thermostat Settings
If the fan settings on the thermostat are set to “On” instead of “Auto,” the fan will run constantly. This will not only prolong the time it takes to warm the heat exchanger up, but it will also allow the fan to circulate air long after the furnace has shut down, at which time the air will be quite cool. Make sure your thermostat is working and set correctly.
Dirty Furnace Filter
The heat exchanger in your furnace is where the air absorbs heat from the combustion process. By moving the heated air into your home, the furnace keeps the heat exchanger from overheating. Any restrictions to this airflow, such as a dirty air filter, will allow the heat exchanger to overheat, tripping the high limit switch and shutting the burners off to prevent heat exchanger damage. If your furnace shuts down prematurely, check for a dirty furnace filter.
Flame Sensor or Pilot Light Problems
If your furnace turns the blower on but the burners are not lit, cool air may be circulated. In modern furnaces, a flame sensor is used to detect the flame and open the gas valve. If this sensor is dirty, the burners will not light, and the system will shut down. Having the flame sensor cleaned can often solve the problem. If you have an older furnace, the pilot light may have gone out or the thermocouple may be damaged. Try relighting the pilot light and make sure the thermocouple is contacting the flame.
Clogged Condensate Drain
In high-efficiency furnaces, nearly all the heat is scavenged from the combustion exhaust for heating the home. This cools the exhaust enough to form condensation, which must be removed with a dedicated drain. If this drain clogs, it can back up into the furnace, tripping a safety switch that shuts the system down. Have the condensate drain cleaned to restore normal furnace operation.
Furnace Repair in Chicago, IL
If your furnace is blowing cold air, our team at ABC Plumbing, Sewer, Heating, Cooling and Electric can help. We offer furnace repair and maintenance throughout the Chicago area, and our talented technicians can handle any furnace problem you may encounter.
Neighbors Are Saying About ABC
“Tom was awesome! He is very personable and explains the whole process well. He did a great job and ensured that he used 5-star service throughout the process. I will definitely use ABC and Tom again in the future for electrical work.”–
“Bill showed up on time to repair our broken air conditioner. ABC kept in touch throughout the day to let me know time he would be arriving too. Bill was professional, friendly, helpful, and knowledgeable. We wound up signing up for monthly care package because Bill and ABC really made…”–
“We were very pleased with the service performed by Brett Pack in performing the annual maintenance of our air conditioning unit. He noted it was low on refrigerant, which he then added after consulting with us. He also made sure we took advantage of all available discounts.”–
“Tom did a super job fixing our electrical problem. He is one of the best electricians I have ever had in my home for repair work. I would highly recommend Tom and ABC Company if you need any type of electrical work. He took his time and explained everything and…”–
“I am so impressed with Chris and ABC Plumbing, Sewer, Heating, Cooling and Electric. His friendliness honest approach to his Job is remarkable. Thanks Chris for making my day and believing that they are still great honorable people out there.”–
“Our AC was not working in the 90-degree summer heat. Josh identified that power was not going to the furnace blower. He identified that power was not going to the furnace breaker. His keen eye spotted that the wire leading into the breaker had frayed. He cut out the frayed…”–
- satisfaction guaranteed
- customer service guarantee
- "no surprises" guarantee
- no-nonsense parts & labor warranty See More +
Our AC Guarantees
- equipment size guarantee
- lifetime installation materials warranty
- AC "level for life" warranty
- the exclusive "no-lemon" guarantee See More +