My Furnace is Not Turning On, What Should I Do? A Florida Tech Answers

November 13, 2020

Why Is Heat Pump Freezing Winter

If you have your thermostat set to a warm temperature but have noticed that it’s not turning on, you’re likely experiencing a minor issue that we can help you with.

While some issues may require professional help, you can fix a handful of problems yourself.

If your furnace isn’t turning on, you should start by checking:

  1. Your thermostat
  2. Your air filter
  3. Your circuit breaker
  4. The blower cover
  5. The condensate pump and line
  6. Furnace switches

Below, we’ll walk you through each of these steps, so you can get a better idea of what is preventing your furnace from turning on.

If you have a feeling your furnace issue is serious or would rather have it handled by a team of pros you can trust, reach out to us. We’d be happy to help you determine exactly what’s going on and what can be done to get your furnace working again ASAP! Learn more about the furnace repair services we offer or schedule service!

Step 1: Check your thermostat

Check Your Thermostat

If your furnace isn’t turning on, the first thing you should do is check your thermostat.

For your furnace to work correctly, the thermostat...

...Batteries need to be charged (check the batteries and replace them if they are dead)

...Setting needs to be on HEAT

...Fan setting needs to be on AUTO

If your thermostat is not on HEAT and AUTO and/or doesn’t have fresh batteries, it may not turn on. If you have checked your thermostat and everything looks good, keep reading.

Step 2: Check air filter

The next step is to check your air filter. If your air filter is clogged, it will reduce the airflow to your furnace, which can cause your furnace to overheat and shut off.

On average, you should replace your air filter every 1-3 months or whenever you notice that it’s dirty. If your air filter looks like the filter on the right, it’s dirty and needs to be replaced.

Dirty Vs Clean Fiberglass Air Filter1

To keep your furnace from shutting down in the future due to overheating, check your air filter regularly and replace it when necessary.

Step 3: Check your circuit breaker

Your furnace may not be turning on because the circuit breaker has tripped.

To check if this is the issue, head to your breaker box.

If the circuit labeled furnace has moved to the middle or neutral position, the breaker has tripped. Our advice would be to turn the breaker off, wait 30 seconds to one minute and then flip the breaker back on.

If your furnace stops working again and you notice that the breaker has tripped for a second time, it’s time to call an HVAC tech. Do not attempt to reset the breaker again, as this could damage your home and furnace and could pose a safety hazard to you as well.

Step 4: Check the blower cover

If your furnace was recently maintained or you took the cover off of your furnace to check something, the blower cover may not be on as tightly as it needs to be.

Many furnaces have a safety feature called a blower door safety switch that prevents the furnace from turning on if the blower cover is not secured tightly.

Check the cover of your furnace – if it's slightly loose, that could be your issue.

Step 5: Check the condensate pump and line

Condensate Pipe And Line

Condensation is a byproduct of high-efficiency furnaces. To help combat this, high-efficiency systems are equipped with a condensate drain to move condensation out of your home.

Many times, your system will also have a condensation pump that will help to actively pump this water out of your home.

However, if there is a block in the pump or condensate drain line, water may back up in the system, triggering the system to shut down to prevent water damage.

If you do have a condensate pump and you notice that it’s not running, there’s likely a blockage in the pump that a tech will need to clear.

If you don’t have a condensate pump but notice water around the bottom of your furnace, you could have a blockage in your condensate drain line. You’ll want to have a tech come and assess the clog and remove it.

Step 6: Check switches

Your furnace may not be turning on if it has sensed any unsafe conditions which have triggered one of the safety switches to turn off your system.

There are a variety of safety switches in your furnace that each monitor a certain part of your furnace and will trigger the system to shut down if that part isn’t working like it should.

These switches include:

  • Pressure switch
  • Flame sensor
  • Limit switch
  • Flame rollout switch

Newer furnaces may show you a “code” as to which safety switch has been tripped. This is usually in the form of flashing lights. To understand which code your furnace is blinking at you, you’ll probably need to read your furnace manual.

Regardless of whether you are able to determine which switch has been tripped or not, you should reach out to an HVAC professional for help if you think a tripped switch is your issue. Likely there is either a legitimate issue that has caused one of the switches to trip or there is an issue with one of the switches themselves. Either way, you'll need a professional to safely determine the issue and resolve it correctly.

Still can’t get your furnace to turn on? Hire the best pros in Tampa: Red Cap!

Feel like you've exhausted your options? Reach out to us. We’ve been trained to correctly diagnose and repair all makes and models of furnaces, so regardless of what’s going on with your system, we can figure it out and get your furnace working in no time.

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