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Furnace On But No Heat? Possible Causes and Solutions


If you’ve ever found yourself shivering under blankets while your furnace confidently hums away, seemingly oblivious to your desperate plea for warmth, there are options for you.

And we have the info you need.

Read on to learn about the possible causes of and solutions for having a furnace on but no heat.

Thermostat Issues

When facing issues with a furnace that is on but not producing heat, one of the first areas to investigate is the thermostat. Ensure that the thermostat settings are correctly configured to the desired temperature.

Check for any signs of malfunction on the thermostat itself, such as a blank display or unresponsive controls. If your thermostat operates on batteries, replacing them might be a simple solution. 

You may also want to take measures to prepare your heating equipment, including your thermostat, before the cold weather hits.

Pilot Light or Ignition Problems

The pilot light serves as the ignition source for the furnace burner, and if it’s extinguished, the furnace won’t be able to generate heat.

If you have a gas furnace with a traditional pilot light, visually inspect it to see if the flame is lit. If not, carefully follow the manufacturer’s instructions to relight it.

In some cases, a faulty thermocouple may be causing the pilot light to go out. If the thermocouple is malfunctioning, it may need replacement.

For newer gas furnaces equipped with electronic ignition systems, a malfunctioning igniter can be a common issue. The igniter is responsible for sparking the gas and initiating combustion.

If the igniter is faulty, it won’t ignite the gas, leading to a lack of heat. Consider checking the igniter for signs of damage or wear. If needed, replacement of the igniter may be necessary.

Dirty or Clogged Air Filters

The air filter is important for maintaining proper airflow through the furnace system. Over time, if the filter becomes laden with loose dust and debris, it can clog up the airflow, which can make the furnace overheat and trigger safety mechanisms that shut down the heating element.

Start by locating the air filter within your furnace system. Depending on the type of furnace, the filter might be located in the return air duct or within the furnace unit itself.

Take a look at your air filter regularly and clean or switch it as recommended. Disposable filters should be replaced, while reusable ones can be cleaned based on the provided instructions.

Clogged or Blocked Vents

Clogged or blocked vents are another potential culprit when a furnace is running but fails to produce heat. Vents help distribute heated air throughout your home.

If vents are blocked, or if there is a significant build-up of dust and debris, it can impede the airflow, causing the furnace to operate inefficiently.

If none of these solutions work, you might need to look into replacing your HVAC unit.

Furnace on but No Heat: Now You Know

Furnace on but no heat? Hopefully, you can solve your problems now. 

Are you looking for HVAC help in your area? With over 100 years of combined experience, the team at Ultimate Comfort is here for you. We aim to treat our customers respectfully and fairly, and to resolve their problems quickly.

Contact us today to get started.

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