Basic Furnace Troubleshooting Tips You Should Know

Posted: 2022-10-06

This winter, your furnace will be an indispensable piece of equipment. Without it, your family would be squeezing around wood fires to stay snug. But your heating system is only as good as it is when you give it regular professional maintenance and standard owner upkeep.

That said, your furnace is still an appliance that can experience breakdowns and develop problems that can affect its proper functioning. So, if your unit is acting weird, like it doesn’t want to turn on, you should be knowledgeable with a few simple troubleshooting steps before calling the experts.

Four Seasons Air Specialists is your reliable heating company in Mahtomedi MN. In this article, we’re going to give you easy tips to help you understand your furnace a little bit better.

Basic Diagnosis

One of the first things you need to determine is that the system has power. Find the service panel and make sure the circuit breaker to your furnace or air conditioner is not tripped. Your HVAC systems will have their dedicated circuit breaker or fuse (for older electrical systems). Turn the breaker off for the specific unit acting up and wait about ten seconds and turn it back on. If your home is equipped with fuses, switch the main power off. See if there are any blown or burnt fuses and replace them accordingly. Then, check the thermostat for power. If the problem persists, call your trusted HVAC contractor.

Pilot Light Issues

If your furnace is equipped with a standing pilot, make sure that it is lit and the flame is touching the tip of the thermocouple. If it is not, you can use our thermocouple replacement guide on your user’s manual for further troubleshooting.

If the pilot is lit but the main burners do not come on, try to feel the side of the furnace. If the side of the furnace is cool, the problem could be the thermostat, furnace control board, limit control, or gas valve. That should save you some time finding out the root cause of the problem.


When the airflow is compromised, your HVAC system will experience short cycling, causing the unit to shut down before the heating or cooling cycle is completed. Most of the time, cleaning or replacing the filter resolves this problem.

However, check the evaporator coils, usually found inside the air handler, if the issue remains. In some units, the coils are attached to the furnace. If there is ice or frost on the coils, shut the unit off and let it thaw.

Another possible reason for an HVAC system to short-cycle is a faulty thermostat that does not get the right temperature reading. You will notice that the room does not reach your desired comfort levels or warms or cools too quickly.

Blocked Air Vents and Registers

Sometimes, your furnace is working but your rooms aren’t getting the proper heat or airflow. So, check your entire home for all the supply and return grilles. They should all be fully opened and clear.

Make sure there are no rugs, furniture, or anything else blocking the flow of air. Not only will blocked vents and registers minimize your comfort, but they can also lead to duct leaks due to excessive air pressure and untimely HVAC repairs and breakdowns. Closing off vents and registers in unused rooms is not recommended. You won’t save any extra money but will end up causing more problems for your heating system—something we’re sure you don’t want to deal with.

Unusual Flame

Your furnace’s flame should be a bright blue, with perhaps a small yellowish tip. The blue flame shows that your furnace is burning the fuel safely and efficiently.

If the flame is red, yellow, purple, green, or any other color than blue, it indicates a problem with the combustion system. In this case, contact a professional right away. Do not try to fix your furnace flame color on your own, especially if you don’t have proper training. It’s a safety issue.

Ask Four Seasons Air Specialists

For hassle-free Grant furnace repair and maintenance, be sure to talk to one of our heating experts. We’ll guarantee your unit will work according to the manufacturer’s specifications.