5 Reasons Your Heater is Not Working and How to Fix It

Ahh San Diego. It doesn’t get cold…right?


Well maybe half wrong. I suppose it all depends on how you look at it. Someone from Canada would find winter in San Diego to be a heat wave.

But here in San Diego, we’ve been experiencing an exceptionally cold start to winter. 30 degree temperatures and ice greet cars in the morning, something that usually isn’t present until the deep of winter.

With all this extra cold, it’s no wonder you’re concerned when your heater is not working.

No one likes to deal with heater repairs, let alone in the middle of a cold snap.

We’re here to help you get your heater fixed and back to doing what it does best as quickly as possible. So to help you figure it out, here are 5 reasons your heater may not be working and what to about it.

Why is My Heater Not Working?

#1 Your Gas Valve is Off

While this may not be the first solution you think of, and it’s also very not likely the case, it is still a possibility.

If you recently had service performed on or around your furnace, or if a contractor had to get work on your roof near the furnace exhaust, there is a chance they turned off the gas valve and didn’t turn it back on.

Check the pipes coming out of the your furnace and look for a small nob. If it’s turned off, no gas can reach your furnace and therefore you’ll find that your heater is not working.

#2 Your Thermostat is Not Working

This may sound kind of like the silly tech support question “Is your computer plugged in and turned on?” but you’d be surprised as to how often your thermostat is the culprit.

If your heater is not working, check to make sure the thermostat is not showing an error. If all is good, verify that it’s set to HEAT mode.

If you set the thermostat to 72 degrees, but have it set to COOL, you’ll be waiting until Summer for your HVAC system to kick on.

Your next step, if those didn’t work, is to set the thermostat 5-10 degrees warmer than you want it. It could be that the air temperature around the thermostat is already at the desired temp, even if the rest of the house is cold.

If your thermostat is by a window that receives a lot of sun, this could often be the case.

Woman programming thermostat

#3 Check the Breakers

After confirming that your thermostat is working properly, your next order of business should be to check the breaker.

You’d also be surprised how often we receive calls to schedule a furnace repair to only receive a call an hour later cancelling because it was flipped breaker.

Now that we’ve got the two easiest solutions out of the way, let’s dive into some problems that might take a bit more investigation.

#4 Change Your Air Filter

Did you know your furnace has an air filter? Many of our customers don’t realize that their air filters need to be changed at least twice a year.

We’ve seen some pretty nasty filters in our more than 30 years of providing HVAC repair services in San Diego. Some filters look like they haven’t been changed in those same 30 years.

What this means is that dirt, grime, and dust all build up on your air filter. When the filter is plastered in grime, air can’t make it through the filter properly.

This results in poor or non-existent air flow, causing your heater to not work like it should.

You can buy an air filter and change it yourself, or Precision Temperature will take care of it for you as part of our furnace maintenance service.

#5 Your Furnace is Short Cycling

What if your heater is working, just not like it should? You notice that, normally, when it kicks on, it stays on for about 20 minutes.

But now your furnace is turning on and off again after every minutes. A lot faster than it should.

This is called short cycling.

This means something is wrong with your furnace. It’s not heating the home like it should, and it’s probably costing you more money on your energy bill because it’s running more than it needs to be.

If your heater is short cycling, this usually means that your furnace is overheating, your air filter is too dirty, your flame sensor isn’t working, or your furnace is over/undersized for the space you’re trying to heat.

The first few problems on that list can be solved with a simple furnace repair. But if you’re unfortunate enough to have the last issue, I have bad news for you.

The company you (or the previous owners of your home) used to install your furnace either undersold a system to get you to close the deal, or oversold the system to make an extra buck.

You’ll need to contact an HVAC company like Precision Temperature to provide a free estimate for furnace replacement to get you system that’s designed for the size of your home.

Need Help with Your Heater Not Working?

If you still need help, Precision Temperature is here for you. Give us a call at 619-588-5321 and one of our friendly office staff will be able to help you schedule an appointment for a furnace repair.

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