How to Troubleshoot and Reset Furnace?

If the furnace stops functioning correctly, there are a few things that practically any homeowner can do to try and fix the issue.

To troubleshoot your furnace, check the thermostat settings, the furnace switch, and the breaker; replace the dirty filters and tightly close the front panel. Sometimes, resetting the furnace would solve the problem – in case there is no reset button, turn the unit off and back on at the circuit breaker.

How to Troubleshoot and Reset Furnace?

In a lot of cases, any minor issues with your furnace can be fixed with a simple reset. Just turn the unit off, wait for 10 seconds, and turn it back on again. 

To troubleshoot the furnace, you might want to:

  1. Check the thermostat settings and make sure that the device is functioning correctly
  2. Inspect the furnace switch (some of them come with a fuse and your furnace will stop operating if the fuse is blown)
  3. Ensure that the breaker hasn’t tripped
  4. Properly close the front panel
  5. If you have a gas furnace, check the pilot light
  6. Replace any dirty filters
  7. Make sure that the registers are not blocked
  8. Ensure that nothing is blocking the fresh air intake

Read: Can You Install A Furnace Yourself?

How Do You Troubleshoot Your Furnace?

  1. Changing the filter can make a huge difference – make sure to check the air filter every 30 days and change it as soon as it becomes dirty.
  2. Check the thermostat – it has to be set to ‘heat’ and located in a proper place. You might have to clean an electromechanical thermostat and change the batteries in battery-operated ones.
  3. Set the thermostat temperature 5 degrees higher than the current room temperature. 
  4. Ensure that the furnace switch is turned on, that power is turned on at the breaker box, and replace any blown fuses. You might want to reset the furnace at the breaker at this point.
  5. Check the pilot light and gas valve.

Why Is My Furnace Not Blowing Hot Air?

There are a few reasons why your furnace might not be blowing hot air:

  • Issues with the thermostat
  • A clogged filter
  • Failure of the high limit switch
  • Problems with electricity or gas
  • Leaky ducts
  • Issues with the pilot light, gas valve, burner, or flame sensor

Can Hear Your Furnace Click On But It Does Not Fire Up?

In a lot of cases, a furnace clicking but not firing up would indicate an ignition system malfunction. This might include issues with the thermocouple, the pilot light, or the gas valve.

Read: How Much Is A New Furnace For A 2000 Square-Foot Home?

What Does a Blinking Light Mean on My Furnace?

Typically, when you see a flashing light on a furnace, it means that the unit is trying to send you an error code. A solid light, in its turn, usually indicates that the furnace is working perfectly fine.

If you see a blinking light, you should consult the user’s manual as different models would have different meanings for their error codes.

Will a Bad Thermostat Cause the Furnace Not to Work?

The truth is that one of the most common furnace problems is a bad thermostat. 

Here are some of the issues that a malfunctioning thermostat can cause:

  • The furnace is not blowing any hot air (wrong thermostat settings, dead batteries, or wiring issues can be to blame)
  • The house feels hotter or colder than it should be (the thermostat might have been placed in an improper location)
  • The furnace is short-cycling (poor thermostat placement and faulty wiring can cause that)

Why Is My Furnace Just Blowing Cold Air?

The chances are high that there is an issue with the flame detector, the air filter, the condensate lines, the pilot light, or the gas supply if your furnace is blowing cold air. However, do check the thermostat first.

Read: Why Furnace Ignitor Lights But No Flame? How To Troubleshoot?

Can Hear Furnace but No Heat?

If no heat is coming out of the vents, then there might be an obstruction in the system. Dirty air filters, for example, can restrict airflow.

What Would Cause a Gas Furnace Not to Ignite?

  • Issues with the gas line
  • A faulty thermostat
  • A dirty air filter
  • Malfunctioning pilot light or ignitor
  • Dirty gas burners
  • A broken flame sensor

How Do You Know If Your Furnace Ignitor Is Bad?

  1. The furnace shuts down completely – if the ignitor is bad, the unit will turn off as a safety measure
  2. The furnace is blowing cold air – if the ignitor is not able to light the burner, then you won’t have any heat
  3. The furnace is short-cycling – if the unit senses a safety problem, it might turn on and off repeatedly
  4. The ignitor is not glowing – a correctly functioning ignitor should get extremely hot and then start glowing

Read: Furnace Clicks But Doesn’t Turn On – Troubleshooting Guide

How Do You Force a Furnace to Restart?

To force your unit to restart, you can always turn it off at the circuit breaker. Find the furnace’s breaker at the main circuit breaker box and turn it off.

Ideally, you would want to leave the system that way for around 10 minutes. After that, flip the furnace breaker back on.

Where Is the Reset Button on Furnace?

Not all furnaces have a reset button, but the majority do. To locate it, you would have to remove the access panel from the blower motor housing and look for a button on the side of the blower motor (be careful, as the housing might be hot). 

How to Restart a Furnace Pilot Light

If you have an old furnace with a pilot light, then you might have to manually restart it, at one point. Before doing that, make sure to turn the unit off and give it some time to cool down.

Ducane Furnace Reset Button

If your Ducane furnace’s ignitor is not glowing, you can try pressing the reset button located in the center of the rollout switch.

Bryant Furnace Reset Button

To find the reset button on your Bryant furnace, in the majority of cases you would have to locate a silver box – you’ll find a white or red button right above it.

Read: Bryant Furnace Code 33 – Troubleshooting Guide

Nordyne Furnace Reset Button

Sometimes, a Nordyne furnace limit switch will have a reset button right on it. Look at the wiring diagram and follow the wires from the power source to the switch – the reset button is the small button between the wires.

Furnace Reset Button Keeps Needing Resetting

If you have pushed the reset button, but it keeps popping up, then you shouldn’t keep pressing it. The chances are high that the unit is overheating and only an HVAC technician would be able to deal with the problem. 

What Causes a Furnace to Need to Be Reset?

A reset button is, basically, a safety feature. It will trip if there is something wrong with the furnace and you can use it to manually shut down a unit if it ever gets too hot. 

How Long Does It Take for a Furnace to Reset?

If you’re resetting the furnace at the breaker, it is usually recommended to wait for 10 minutes before switching it back on.

If you are using a reset button, then holding it down for about 10 seconds would be enough to reset the unit. 

How Do You Know When Your Furnace Needs to Be Replaced?

No matter how good you are at troubleshooting, you would have to fully replace your furnace at one point.If your unit is over 15 years of age, it constantly needs repairs, and it has become unusually noisy, then it’s time to get a new furnace.