Lennox Air Conditioner Troubleshooting

Troubleshooting your Lennox air conditioner is easy. You don't even have to call an HVAC professional to do it. We've researched how to troubleshoot your Lennox AC when you think there is a problem. 

To troubleshoot your Lennox air conditioner, you must:

  1. Inspect the remote control
  2. Check the fuse, circuit breakers, or the switches
  3. Check the air filters
  4. Inspect the inlets and outlets
  5. Reset the air conditioner

This post will further discuss the detailed troubleshooting of a Lennox air conditioner. Please keep reading for more information about Lenox air conditioning units. So, let's now delve into the details!

A Lennox manufacturing company photographed outside, Lennox Air Conditioner Troubleshooting

How To Troubleshoot Lennox Air Conditioners

If you notice that your Lennox air conditioner is acting up, that doesn't mean you need to call a professional immediately. We suggest you conduct simple troubleshooting first. See the details below as your reference:

A Lennox emblem photographed up close

1. Inspect the remote control

Inspect the remote control of your air conditioner to see if the batteries are still good. The batteries may be low and prevent proper command of the air conditioner.

2. Check the fuse, circuit breakers, or the switches

Technician checking the AC circuit board for any anomaly

If the first step doesn't make the air conditioner function properly, try to check the circuit breaker if it is tripped. There is a possibility that the fuse is also blown. And lastly, check if there are open isolating switches. 

3. Check the air filters

AC specialist checking the ac air filter for dirt or damage

Checking the air conditioner's filter is the most common troubleshooting. Dirty air filters can hinder an air conditioner's efficiency and proper performance. So, inspect them to determine if they need cleaning. Remove and wash them with water and dish soap or vinegar, and dry them thoroughly. 

4. Inspect the inlets and outlets

The inlets and outlets are also essential to check. You should inspect if there is blocking and interference occurring. If there is, keep the inlets and outlets free from it. 

5. Reset the air conditioner

If all the steps didn't work to make your Lennox air conditioner back to working in its normal state again, it is time to reset your unit. However, remember that it is a must not reset more than once. And if it still doesn't work, your last resort would be to call an HVAC professional.

How To Reset A Lennox Air Conditioner

  1. When resetting, the first thing to do is switch the air conditioner off.
  2. Check where the circuit breaker box is and locate the breaker for your air conditioner.
  3. Reset the air conditioner with the circuit breaker.
  4. Wait for a minute.
  5. Switch the thermostat on again.

Troubleshooting A Thermostat

A thermostat set to 74 degrees

You also have to troubleshoot a thermostat when you find your air conditioner not working since this may be why. To start, you must:

  1. Check the batteries and replace them if necessary.
  2. See if there is a tripped breaker, so you have to inspect the circuit panel.
  3. Check all the electrical connections to see if there is loose wiring. You must remove the device from where it mounts to check the wire contacts. After that, follow the owner's manual to guide you to the next step.

Common Issues Of A Lennox Air Conditioner

These are two common issues that directly need the help of an HVAC professional:

1. The unit is operating too loudly

We think almost all air conditioners encounter this particular issue, and the reason is maybe because of the following:

Fan Motor

In most older air conditioning units, the bearings of the fan motor are wearing out, which is what primarily causes a noisy air conditioner. Due to old age, they can not work properly like before. Replacing them would be much better than replacing the entire air conditioning unit.


Another air conditioner component that tends to wear out is the compressor. The more it pumps, the more it deteriorates. The only solution here is to replace the compressor or the entire unit, depending on what you need.

Read more: "Why Is My Air Conditioner Compressor So Loud?"

Fan blade

It is the simplest component to look into when your air conditioner gets noisy. Since the blades tend to loosen over time, you need to check and tighten their setscrews.

2. The unit won't blow cold air

If your Lennox air conditioner starts not to produce cool air, it is time to inspect its:


Since the compressor is the one that does almost all the work, you have to check it thoroughly. Sometimes, some of the other components contribute to or affect the compressor's performance.

Power cut off

With this issue, you must look into the disconnect box or the fuse and breakers between your air condensing unit and circuit breakers.


Check the batteries of your thermostat or if the device still works fine. If it is a faulty thermostat, it will not command the air conditioner correctly to achieve the exact temperature you require. 

FAQs About Lennox Air Conditioners

Here are some FAQs that you may want to check and see if these can answer some of the additional questions running through your mind.

Is Lennox Air Conditioner A Good Brand

Lennox air conditioner brand has a good name in the industry since its goal is to provide the cleanest, coldest, and most quiet operation. We can say that Lennox is a reliable brand. With proper maintenance, your unit can last longer than usual. 

Suppose we talk about the air conditioner brand and model with the highest SEER rating. The answer will be the Lennox XC25. And almost all of Lennox's model holds a high SEER rating which gives the brand a reputation for efficiency and reliability. 

How Long Does A Lennox Air Conditioner Last?

The air conditioning units of Lennox can last up to 15 years. And that can exceed a little longer as long as you maintain the unit well. 

Read more about: "How Long Does A Lennox Air Conditioner Last?"

Can I Replace Just The Outdoor Air Conditioning Unit?

A huge white air conditioning unit mounted on steel brackets on the wall

Yes, you can replace the outdoor unit of your Lennox air conditioner. However, expect that the unit won't work as efficiently as before.

Can I Replace A Lennox Air Conditioner Myself?

The answer will be no. Replacing an air conditioner unit is not as easy as it seems. It would be best to ask the help of an HVAC professional if you want your unit not to have any operational issues.

Can I Replace Only The AC Coils?

Yes, you can replace only the coils of your air conditioner. However, you should only change them if you have ensured that they are impossible to fix. But if the coils are not the only thing that functions poorly, we suggest that you perform an entire diagnostic test for your unit to know if you need to have a new system.

How Often Do Evaporator Coils Need Cleaning?

Cleaning the evaporator coils of your air conditioner is a must. And it would be best if you clean them at least once a year. If both condenser and evaporator coils are dirty, they will consume more energy and let the system work harder. And to be specific, the energy consumption will increase by 30%.

How To Know If The Air Conditioner Coils Are In A Bad State?

  • If the air vents are pumping warm air
  • The air coils are faulty if your air conditioner switches on and off regularly without adequate cooling
  • If the unit produces weird and irritable noises such as banging, clanging, and hissing
  • You'll know if the coils are impaired if the indoor unit is leaking
  • If the unit doesn't turn on, even if you try to switch it on numerous times

Why Is My Lennox Air Conditioner Not Cooling My House?

If your air conditioner is on and the thermostat is working fine, but the unit's system is not cooling the area, you may want to check the condenser. You have to inspect it to see if it's dirty or if there is something that is blocking it. All you need is to inspect the outdoor unit, clean it and remove the weeds, shrubs, or anything that blocks it.

Why Is My Lennox Air Conditioner Not Turning On?

The most typical reason why your air conditioner won't switch is because of a tripped circuit breaker. So, check it immediately. And if the unit won't still turn on, you might want to check the thermostat next. If it is faulty, it won't correctly communicate with the air conditioner.

What Is The Difference Between Single-stage And Two-stage Air conditioners?

The former's compressor only operates at one level of operation. And that is to cool your home at maximum capacity. On the other hand, a two-stage air conditioner has two levels of operation. First, it can work high during summer. And second, moderate to low for colder days.

In Conclusion

A Lennox manufacturing company photographed outside

You can quickly troubleshoot your Lennox air conditioner now since we have already explained how to do it. Plus, we have also provided more information that might help you out. Suppose the above guidance still can't help solve your acting up Lennox air conditioner. In that case, we suggest you call for an HVAC professional to solve every problem your unit is facing.

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