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AC Not Keeping Up on a Hot Day?

Published April 21, 2023
Written by Eric Smith
AC Not Keeping Up on a Hot Day?

The Wisconsin Master Tradesman’s Guide to help your lagging AC beat the heat.

Complaints of underperforming AC systems fall into two major categories. In the first camp are customers whose air conditioning has been working perfectly fine for months or years-until recently. This can be perplexing and frustrating. Fortunately, though, some of these mechanical breakdowns can be addressed at little or no cost.

On the other hand, you might honestly feel that your AC has never quite worked properly (and it’s only getting worse). If that sounds like you, the good news is you’re not crazy. Unfortunately, what’s causing your AC to lag behind may not be fixable at home. Read on to learn more.

Maintenance Items That Can Cause An AC To Struggle To Keep Up

1 – Problems with Airflow

Uninhibited airflow in, around, and throughout your AC system is critically important for the machine to function properly. Let’s troubleshoot, beginning with issues that could be restricting airflow around the unit.

  • Plugged Furnace/AC Filter

The filter in your air conditioner serves two purposes. The first is to protect the air conditioner coil, which would otherwise become rapidly coated with dust and other large particle matter. The second and most obvious purpose of the air filter is-you guessed it-to filter the air you breathe at home. Your filter is the first thing you should check for blockage that could be causing poor overall performance.

What to do: Replace the filter regularly. To be specific, you should install a fresh, 4-inch air filter at least once per “season” (twice a year in Wisconsin). If you have a 1″ air filter, you may need to replace more frequently, up to once a month!

  • Plugged Outdoor Condenser

The condenser is the outdoor portion of your air conditioner, and it needs to breathe, too. Step outside and inspect the coil on the outside unit. If it’s visibly dirty, that’s problem #1. If you’re trying to check, but the coil is hidden by branches or shrubs, that’s problem #2.

What to do: First, make sure to clear any shrubs surrounding the unit. A good rule of thumb is 18 to 24 inches of clearance on all sides at all times. Then, simply clean the condenser coil by rinsing it with water.

  • Plugged Indoor Condenser 

Just as with the outdoor condenser, the indoor condenser should have a clean coil that allows it to breathe properly. Otherwise, it will struggle dramatically to produce new, cool air, in direct proportion with how restricted its airflow is. Unlike the outdoor coil, this one’s pretty difficult to observe. It usually requires the removal of doors or access panels, plus a camera or scope to get a real good look at this part of the air conditioner.

What to do: Although you can clean the outdoor condenser coil yourself, we don’t recommend this for the indoor coil. For this issue, it’s better to call a professional.

2 – Other Maintenance-Related AC Issues

Now we’ll look at potential problems that aren’t related to airflow.

  • Thermostat Broken or Low on Battery 

The thermostat is the control center of the entire AC system. If your air conditioner struggles to keep up with the heat even when you have it set to cool, your thermostat may not be accurately sensing temperatures in the home.

What to do: First, put in fresh batteries. Then, check the thermostat’s programing to make sure it’s set the way you like it. Finally, cycle it off and back on once to see if the issue is resolved.

  • The Air Conditioner Needs Repairs

Sometimes an air conditioner acts like it is running when it really isn’t. Ask yourself if any of the following symptoms sound familiar:

  • The outdoor AC fan is spinning, but for some reason, the furnace or air handler is not running.

  • The outdoor AC compressor is running, but the fan is not.

  • The furnace fan is clearly on, but the outside air conditioner is not running.

  • You have noticed ice forming on or around your air conditioner, refrigerant lines, etc.

  • You find water pooling around the furnace or air handler inside the home.

What to do: Call (262)367-3808 for repair so a real AC guru can get out there and take care of you.

Other Common Reasons Your AC Struggles to Keep Your House Cool

Finally, there are some problems that may not be fixable even with a service call.

Extreme Temperatures, Prolonged High Humidity

HVAC systems in Wisconsin are designed so that the heating and cooling systems function even when it’s as cold as -10 degrees outside-or as hot as 90. It’s calibrated to be able to adjust itself back to a comfortable setpoint of 72°F even at these extremes.

If you encounter periods of extremely high humidity or temperatures above 90, there may be nothing wrong with the system itself: it just wasn’t designed to keep up with these particular demands.

Undersized Air Conditioner

Suppose the temperature is a reasonable 75 to 80 out, and your air conditioner is still struggling to keep up. There is a very real chance it wasn’t sized properly when your HVAC company first installed it.

Sizing is important for air conditioners. A system that is too small can run all day long without lowering the temperature by a single degree, while a system that’s too large will fail to deal with humidity in the air and cause a clammy, “wet-cool” feeling throughout your home.

Thermostat Setpoint Too Low

It can be difficult or impossible for your AC to adjust the temperature by more than 20 degrees. If it’s 90 out, there’s no use setting it to 65. However, it should be able to reach 72 comfortably, and sometimes even 70.

Wear on Home & Effects on Efficiency

If your AC worked for a long time without issue, but you now find that it struggles even after routine maintenance and service calls, this may be due to changes in your house, not the air conditioner. Worn windows and doors are among the factors that can cause a struggling AC, since worn-out openings allow excessive heat to penetrate the home.

At the same time, the performance of any air conditioner will decline with age. If updates to your home do not bring satisfactory results, it may be time to upgrade your AC to be able to handle a higher load.

Wearing AC Unit 

An old, worn-out AC, especially one that did not see adequate maintenance throughout its life, might be telling you to say goodbye. You can’t turn back time, but you can always call us.

AC Still Not Keeping Up? Call Austin Plumbing, Heating & Air!

The vast majority of problems that can prevent your AC from keeping you cool are problems we can solve.

Air Conditioner Maintenance & Tune-Up: We follow a process of more than 60 steps to systematically check your AC for problems and make adjustments you may not have realized it needed.

AC Repair: Our trucks are fully stocked to handle whatever we encounter on a service call, but our finest assets are our AC repair technicians. They’re the best of the best, and they’re ready to help you.

AC Replacement: In the most extreme cases, replacement may be your best option. Your input is the only thing we’re missing before we can design an AC system that works just right for you!

About The Author: Eric Smith
Eric Smith is a 3rd generation State of Wisconsin Master Plumber, Water Well Pump Installer, Plumbing Contractor, Water Well Contractor, HVAC Contractor and Water Treatment Expert and the owner of Austin Plumbing, Heating & Air.