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

Sunday, July 8, 2018

When homebuyers ask us why the air conditioner doesn’t seem to be working so well after we turn it on for the first time in months to inspect a foreclosure house, the a/c is often working just fine. But it has three types of heat to overcome after startup:

  1. Cooling the air - Every air conditioning system has to do this, but a system that has been off for a while also must contend with the additional loads from the next two items.
  2. Removing the heat contained in the water vapor in the air  - Because the humidity in the air contains additional heat—called “latent heat”—it must be removed as part of the initial dehumidification and will slow down the cooling process.
  3. Walls, furnishings, and ducts contain heat - As the cool air flows through the ducts and out into the rooms, it absorbs heat from the all the surrounding warm surfaces until they also cool down. 

    The “temperature split,” which is the difference between the temperature of the air going into the air handler (indoor unit) and the air coming out, is the number we check to determine whether the system is operating satisfactorily until the startup heat loads have been removed.

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

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

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

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

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

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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