There’s nothing more inconvenient than a furnace that won’t turn on when you need it the most.
If you’ve found yourself in this situation, we’re here to help you troubleshoot the problem. But first, be sure to check your thermostat and make sure it’s in the ON position and turned to HEAT.
If you’ve checked the thermostat settings and your furnace still won’t turn on, you may be dealing with one of the following common issues that can be fixed by a professional:
- Tripped circuit breaker
- Broken or malfunctioning components
- Faulty thermostat wiring
- A safety feature is triggering
In this blog, we’ll dive into these issues in detail and explain how a professional can fix them.
Issue #1: Tripped circuit breaker
After you check your thermostat, you’ll want to find your electrical panel and see if your circuit breaker has tripped. This is important because if your furnace’s circuit breaker has tripped, the power going to your furnace has been cut off. This could explain why your furnace won’t turn on.
To fix this, you’ll need to reset your breaker. Here’s how:
- Locate the switch labeled “furnace” in your electrical panel.
- Is the switch in a different position than the rest of the switches? If so, flip the switch OFF by turning it to the right.
- Then, flip the switch to ON by turning it to the left.
After you reset the switch, wait 30 seconds to see if the breaker trips again. If this happens, you’ll need to call a professional and schedule a repair appointment. Do NOT try to reset the switch again, as you may have electrical issues that need to be fixed.
Issue #2: Broken components
Furnaces are made up of a variety of components, including:
- The blower motor
- Circuit boards
- Flame sensors (older furnaces)
- Electronic ignition systems (newer furnaces)
As with most household appliances, components within a furnace can and will eventually fail or malfunction over time due to normal wear and tear. When this happens, your furnace may not turn on. A professional HVAC technician will be able to identify and fix or replace any broken parts.
But before you call a pro, double-check the following:
Your furnace power switch is set to ON. To do this, go to your furnace and look for a switch that resembles a normal light switch that’s typically attached to the air handler. If the switch is in the OFF position, switch it back ON. It’s possible that someone or something may have unintentionally switched this off.
Issue #3: Faulty thermostat wiring
If you’ve checked the thermostat settings, the circuit breaker and the furnace ON/OFF switch and your furnace still won’t turn on – you could be facing a problem with the thermostat wiring.
Depending on the age of your furnace, the wiring could be frayed. Over time, wiring can short or fray which prevents electrical signals that are being sent from the thermostat from reaching your furnace. Unfortunately, this isn’t something you will be able to fix on your own. Call a professional to inspect your wiring and replace any faulty wires.
Issue #4: Triggered safety feature
Many modern furnaces come equipped with safety features to prevent dangerous electrical situations and keep you and your home safe.
The two most common safety features are the float switch and the flue gas spill switch. If either of these safety features has been triggered, your furnace will not turn on.
The float switch can be triggered if your furnace’s condensate line is clogged. If this is the case, a professional HVAC tech will clear the condensate drain pan of any clogs and reset the float switch.
Flue gas spill switches are found in newer gas furnaces and are designed to prevent carbon monoxide and other dangerous gases from leaking and entering your home. If, for some reason, gases aren’t being properly vented outside of your home, the gas spill switch will trip and shut your furnace down.
In this situation, a professional HVAC tech will inspect the flue gas spill switch, make sure that all gases are being properly vented and reset the switch.