How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

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How do I determine the age of my air conditioner if the serial number is missing or not legible?

Thursday, September 7, 2023

If the data plate on the air conditioner is missing or so faded that it is no longer readable, you already have part of the answer. It’s a least 10 years old. But, if you need a more specific age, here’s four ways to find it:

1) Check building permits. You may be able to get the date of the permit for replacement of the system from your local building department. If they don’t have a permit on file, then the unit is either original to the construction of the home or was replaced without a permit.

2) Check data plate at other half of system. If it is a split system, and both parts of the system have the same manufactuerer and paint color on the cabinet. So check the air handler data plate if the one on the condenser is illegible, or vice-versa.

3) Ask for homeowner’s paperwork. Many homeowners keep the owner’s manual and payment receipt for their system. However, relying on only the homeowner’s memory for the age if that’s not available can be a mistake. “We just replaced it a few years ago” sometimes turns out be 10 or more after age is verified by another means, especially for seniors.

4) Condition of condenser - Condensers (outdoor units) age at different rates according the weather and sun exposure where they are located. But an experienced home inspector can provide an approximate age based on condition. Air handlers are more difficult to age based on condition, but there is usually more than one data plate to check for serial numbers. 

    To determine other key specs of your HVAC system, see one of these other blog posts: 

How can I find out the SEER of my air conditioner?

How can I tell whether the condenser (outdoor unit) is an air conditioner or heat pump?  

How can I find out the size of my air conditioner?  

  To learn more about heating and air conditioning systems, see these other blog posts: 

My air conditioner won't turn on. What's wrong?

• What is the best location for a heat pump condenser (outside unit)?

• What is the best location for a heat pump air handler (indoor unit)?  

How can I find out the size of my air conditioner? 

Where is the air filter for my central air conditioner and furnace? I can’t find it? 

Does an old air conditioner use more electricity as it ages? 

How did homes stay cool in Florida before air conditioning? 

What is wrong with an air conditioner when the air flow out of the vents is low?

Why has the thermostat screen gone blank? 

Why does it take so long to cool a house when an air conditioner has been off for a while? 

Why is my air conditioner not cooling enough? 

What are the most common problems with wall/window air conditioners?  

Will closing doors reduce my heating and cooling costs? 

   Visit our HEATING AND AIR CONDITIONING page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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