10 Must-Know Tips for Your Air Conditioner

During the summer, air conditioning can cause really high electric bills, and I would hate to think that you might be spending more money on electricity than you have to. If you have central air conditioning, here are 10 ways that you can take care of your air conditioner to keep it running efficiently, which will save you money. (These tips are written with the non-mechanic in mind, so you can do them.)

1. Change your air filter every 3 months. Changing the air filter is as important for your air conditioner as changing the oil is for your car. Put in a new filter at the start of summer, and then at least once every 3 months after that. If you live where it is windy or there is construction, or if you have allergies, you might need to change it more often.

When you replace the air filter, there’s an arrow on the side that indicates which direction to place the air filter. The arrow shows the way the air flows through the filter into the unit.

2. Buy pleated filters. Spend a couple of dollars more to buy pleated synthetic filters, not the cheapest fiberglass filters. To get a good filter for a good price, Doug recommends the True Blue pleated air filters at Home Depot with a Filter Performance Rating (FPR) of 5. (He thinks the filters he saw at Lowe’s are overpriced.)

3. Check to see if your air conditioner is cooling efficiently. You can measure if your air conditioner is working the way it’s supposed to by comparing the temperature of the air blowing out of the vent to the temperature of the air going back into the return air vent. There should be 15 to 18 degrees (F) difference between the two temperatures. A higher difference might indicate an issue such as a clogged air filter. A lower difference could mean a problem like your AC is low on Freon. Either way, it’s using a lot of extra electricity when it’s not running efficiently, and it’s time for maintenance.

4. Set your thermostat at a normal temperature. Don’t turn your thermostat all the way down. That won’t help your house cool down faster; it will just make your AC work longer.

5. Protect your ducts. If you’re doing home renovations and knocking down walls like we did, tape temporary air filters over the return air vents on the wall. This will prevent dust from getting into your ductwork. (The filters in the photo above are the cheap fiberglass air filters, not the kind you should buy for your unit, but they were fine for this.)

6. Check your ductwork for leaks. You don’t want all the cold air to leak out into your attic, so check to see if you notice any holes where air escapes. There are two common types of ductwork: flexible ducts and rigid metal ducts. Flexible ductwork is often used because it’s faster to install, but it doesn’t last as long. Metal ductwork lasts longer. If you have holes or leaks in your flexible duct, it’s time to replace it. If you have a leak in metal ductwork, you can seal it with…can you guess? Duct tape. (Yes, that is why it’s called duct tape.)

7. Insulate your ductwork. Ducts usually run through the attic, and it gets hot up there. It’s worth investing money in an extra wrap of insulation around the ducts. Get the insulation wrap that is backed with foil, not plastic, because the plastic breaks down over time.

8. Clean your outside unit annually. Dirt and debris build up on your outside unit (the condenser), which blocks airflow and makes your air conditioner work harder. Once a year you want to wash off the debris; first turn off the power, and then you can use a garden hose. Gently rinse it so the water cleans between the thin metal fins on the condenser. (You don’t want to spray against the fins because they can bend easily.)

9. Secure your outside unit. Your outside unit is a target for theft. It’s not that they want the air conditioner itself, but the copper inside is valuable and can be sold as scrap metal. Keep your unit out of view with hedges or a fence that will also provide shade for high efficiency, but take care not to block the airflow. You can also bolt it down to the concrete base.

10. Collect free water. Air conditioners create a lot of condensate from the air, and that water drips out of your house from the condensate line. During the summer months, our air conditioner puts out over five gallons of clean water from the air every day. Set a water barrel on the side of your house under the condensate line to catch the drips, and use that to water your landscape.

Here in Texas it gets so hot that the days of 95-degree weather seem like a fond memory. At least it’s cooler this summer than it was last year. How hot is it where you live?
About Rachel

I write about practical tips that will help you simplify at home. Connect with me on Pinterest and Twitter.


  1. If you have indoor pets, especially cats or dogs, you should check your AC filter often because it may need to be changed more often than every three months, even if you don’t have allergies. It is amazing how pet hair can clog a filter and ultimately the indoor coil.

  2. I think the filter schedule very much depends on your ac and/or filter type. Our last house had a very hard-to-find and expensive filter, but it only needed to be changed twice a year according to both the ac and filter manufacturers and we never had a problem with that. Our new house, we recently learned the hard way, requires a monthly change. It had been five months and caused a part of our ac to go out because the system was working so hard. But the filters are available at local stores and are much cheaper so it’s not a big deal now that we know. I would definitely check with your manual and/or service person since it varies more than I ever knew was possible.

  3. Thanks for the post. We’re experiencing A/C issues right now. Changing the filter regularly is so important. Theda

  4. I don’t necessarily agree about not getting the cheap filters. Our A/C tech (and my uncle who works with a/c and heating) recommend the cheap filters over the pleated filters. They advised me that this is true b/c the pleated filters can actually cause your unit to have to work harder to pull air through them. Especially with older units, it’s important to make sure air flow is as easy as possible for your unit.

    And I don’t know why I never think of cleaning my outside unit more often. My uncle said that is the first thing he does when working on a unit b/c it is the easiest problem to fix and usually helps quite a bit. Also, covering your unit can help some (both with security and keeping the air around the unit and, thus, the unit itself cooler).

    • Pleated filters can slightly slow down airflow (it’s called “filter drag” or resistance) but most systems are designed for an average pleated filter, and it’s generally preferable to the amount of particles that the fiberglass filters let through.

    • Courtney says:

      Our A/C tech told us the same thing…that the cheaper filters are actually better. We’ve been using the cheap ones ever since with no problems.

      • Our A/C tech recommends the pleated version and because you change them every 3 months, vs. every month for the cheaper filters, you save money. I definitely notice that my house gets dustier when we use the cheaper filters.

  5. Jessica says:

    We live close to Kansas City, MO and our temps have been over 105 degrees for the past two days!

  6. A delightfully cool breeze is blowing in my open window just now. We had a storm that cooled things off. We save our air conditioning for days over 95 degrees when the nights don’t cool down either.
    Margo, Thrift at Home´s last post…A Blue Skirt for Housework, Like Canning

  7. sam rhoades says:

    i love the tip about testing the air temperature at your vents. how do i do this?

    • Hold up a thermometer in the airstream until you get a consistent readout. I use the digital meat thermometer from my kitchen, and it works fine. And it helps if your AC is already on and has been running for a while (i.e., don’t come home and turn on the AC, and then try to measure it right away. The temperature will be dropping too fast to measure accurately.)

  8. I like the idea about putting a bucket out to collect condensation – that’s a new one I hadn’t heard of.
    Mini Mama | Spreadsheet of Life´s last post…Add it up – 65k gone (!) and more of our story out of debt.

  9. We’re sticklers about changing our air filter on time but I hadn’t heard some of these other tips. It’s hot and humid here all summer long and since we just moved here from the Northern US, I’m still getting used to it.
    Steph´s last post…When We Don’t Live Up to Our Expectations

  10. Also, have it serviced every year, right? I’m still new to home ownership, but we’re doing the seasonal servicing for the AC and furnace.

    The AC guy told me to hose off the condenser every time we mowed the grass to keep it cleaner. This being a drought, we haven’t mowed…but something to think about.
    Kacie´s last post…Some new savings goals

  11. No a/c here in Maine, but a lot of these tips also apply to the oil furnace that we have here. Especially the filter changing. I find that when we change the filter more frequently, the house heats up so much better. And when it is 20 below, that is what matters! I hope you all are surviving the heat!
    Heather´s last post…what i am eating #1

  12. Jessica says:

    Here in Iowa it has been near 100 or over for several weeks. We’re getting a little tired of it and so are the crops :(

  13. I’m in England, so no need for A/C this year. De-humidifier maybe…

    • Karen (Scotland) says:

      lol! I’m in Scotland so I get where you’re coming from! Add in towels, wellies and a lovely new umberella and we’re set for summer days out the house…
      Karen (Scotland)

  14. Rachel and any other commenters – I’m curious to know what temperature you set your thermostat to in the hot summer days & nights. Thanks!

  15. Claire Hill says:

    For ac filters – call you nearest commercial ac filter distributor. They sell filters to business by the case, usually 12. Ask if they will sell you a case. They are MUCH cheaper that way and you can change them once a month.

  16. We have a spout over our tub. The water that drips when the a/c is on… that’s clean water?
    Lynn´s last post…Diaper Laundry Helpers

  17. I used to service residential and Marine A/C and refrigeration systems. This is an excellent article and I have two comments.

    1. The reduction of air flow for pleated filters vs non-pleated filters negligible and Not an issue to be considered. I’m surprised any good technician would feel that pleated filter are not the better choice. If one followed their logic producing their conclusion, running the system with no filter at all would be even better that non-pleated filters and no technician would suggest that.

    2. Performance of any A/C is dependent on a few factors, having adequate freon to move the heat from inside to outside. A system can be under or over charged. While overcharging is only possible with the hand of a ignorant tech, undercharge is more common due to a very small leak over time. An undercharged system can easily be observed viewing the condensing unit outside. The suction line, the larger copper tubing of the two, coming from inside the house should be sweating (condensing water) as it enters the unit. This should be so after running 10 minutes or more of run time. That sweating should ideally continue up to the compressor but not so much to cause sweating over the top of the compressor. If the compressor has more than a 1 inch diameter area of sweat as the suction line enters the compressor it is over charged. Undercharging will allow the compressor to run to hot causing failure over time. Over charging will damage the valves in the compressor over time.