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Should I Replace the Furnace When Replacing the Air Conditioner?

HVAC systems require regular maintenances to prevent them from breaking down abruptly. This is because they are such an essential component in your home that offers comfort throughout the year. However, maintenances and repairs are, to some extent, not sufficient.


Replacing old and damaged systems goes a long way in solving substantial repair bills, frequent malfunctions, and accidents. The HVAC system comprises an AC and a furnace, which work in sync to cool indoor air in your home. After some time, it’s always recommended to replace the AC due to several reasons. This then begs the question, should this replacement be done on the furnace too? Let’s try to break it down.

AC Unit Inspection & Repair

Functions of the Furnace in the HVAC System

You need to understand how the furnace works in case of an emergency so that you can quickly troubleshoot problems. The furnace is usually installed inside your house and attached to the condensing unit and thermostat.


This process is a continuous cycle that ensures that you have a regulated environment inside your home, even when the outdoor weather conditions are unbearable.

Here are the steps which it takes the furnace to heat indoor air.

  1. The thermostat in your home detects temperature changes and signals both the furnace and the blower fan in the AC,
  2. Outdoor air blows into the furnace, and your furnace’s gas or fuel source starts heating the air.
  3. The temperature of the air rises, and warm air is pushed through the ductwork,
  4. After the air temperature reaches the desired level, the thermostat sends a signal that shuts the furnace and the blower motor.

However, these machines can’t practically provide service forever, even when taken good care of. Thus, there comes a time when you have to consider replacing a unit or the whole. To help us determine what needs to be changed, let’s see how long they can work.

Average Lifespans of AC units and Furnaces

Air Conditioner or Condensing Unit

Ideally, a well-maintained AC can last upwards of 15 years. It depends on how well the system is maintained and how often you run your air conditioning unit.


The furnace, on the other hand, lasts a little longer. Furnaces have an average lifespan of 15-30 years. However, this depends on factors such as usability, maintenance, and model.

Replacing HVAC Systems – What to Consider

Since both AC and furnaces are highly dependent on each other, ensuring that they are working efficiently together is crucial. This is done by repairing and making sure all parts are working correctly.


Provided that the furnace and the AC have deferring lifespans, it becomes a little challenging to decide if to replace both or one at a time. But here is the kicker, the lifespan of the furnace is almost double that of the AC. This means that you can use one furnace with two AC units.


Therefore, should you replace the furnace and AC at the same time? Yes, if the furnace is twice older than the AC or is completely broken. And no, if the furnace was installed at the same time as the AC or condenser unit.

Experience You Can Trust

Are you experiencing HVAC or air conditioning problems in your home or office? 


You have found the right solution to all your heating and air conditioning issues. At Absolute Airflow, we have a culture we live by where we assure you of no hidden charges, up-front flat-rate pricing, and no overtime charges or surprises.

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Absolute Airflow is a 24 Hour Emergency HVAC Service Contractor

Customer Reviews

Called Absolute for my 81 year old landlord in the height of Summer heat. Scott came out to inspect the old beast of an AC and found many issues. He took the time to educate us, note everything, photograph it and provide several recommendations...and my stubborn landlord has done nothing LOL. A couple months later we asked that Scott come back out and he was there that same day.

Emily H.

Santa Ana, CA

I contacted Absolute Airflow to check my mother's AC, as it was not getting cold. The tech (Scott) arrived earlier than his scheduled time, and was very knowledgeable, professional, and most of very personable with my mother in letting her know that the issue was. Superb customer service Scott and thank you Absolute Airflow! I highly recommend Absolute Airflow.

Billy A.

Billy A.

Bellflower, CA

I have called in Absokite Airflow for my tankless water heater and A/C unit for maintenance. They were professional and took the safety precautions necessary including wearing a mask and cornering their shoes when entering my home. I recommend them highly. Shout out to Zack who took care of the tankless water heater.  They were professional and friendly.

Beatriz S.


Santa Fe Springs, CA

Carlos came to our house to access the A/C project and to give us an estimate. He was very knowledgeable and took his time to explain all the opinions in detail as well as the installation process and warranties. Tanner and Chris were the installers, they were very professional taking their time and attention to details. To keep our house clean while installing the new A/C system.

Robert M.

Robert M.

Whittier, CA