How to Check If Your AC Is Cooling Properly

If you find yourself constantly turning down your thermostat, but your house isn’t reflecting a cool temperature, it’s time to examine your AC unit. Fixing your air conditioner can be costly, depending on the problem. However, you may be able to save some money if you can check out what the problem is yourself. Here’s how to tell if your AC isn’t working properly, as well as probable causes and how to fix them.  

1. Check the Return and Supply Ducts

Before calling in a pro for air conditioner troubleshooting, take a look at the return and supply ducts first to determine whether an expert check-up is necessary. These elements will be located in front of and behind the filter on your indoor AC unit. 

To figure out which duct is which, turn the fan on and place your hand or a piece of paper in front of the entry point. If the paper is sucked in, it’s a return vent. If it blows outward, it’s a supply duct.

From there, place a thermometer of any type (even a refrigerator thermometer) into an access hole in the return duct. If there are no existing access holes in the ducts, you may need to create one with a drill or a hole punch. Secure the thermometer to the access hole and let the machine run for ten minutes. Take note of the temperature after ten minutes and repeat this step with the supply duct. 

When you have the two temperatures written down, subtract the lower one from the higher one to find out the difference between the two. On a properly functioning AC, the difference will be about 20 degrees Fahrenheit. If it’s any less or more, there’s probably something wrong with your machine. 

2. Inspect Your Air Filter

Changing your air filter is an inexpensive, easy fix before calling out a specialist, as a filter tends to cost between $50 to $75. To start, locate your air filter, either within the unit or near a vent by your thermostat. Every unit is different, but you should be able to loosen the grill of the vent, pull the old one out, and insert the new one by looking at the arrows on the filter. 

Be sure the filter is fully in place by tapping it to ensure it doesn’t move before placing the vent on again. This simple act can help keep your cooling costs down in those hot summer months.

3. Look at Your Circuit Breaker

If your air conditioner isn’t running, confirm you have not blown a fuse or tripped a circuit breaker. High-voltage breakers can shut the unit down. Flip the breaker back, and it should start blowing out cold air again. 

4. Monitor Your Thermostat

Sometimes the problem is simpler than you think. Replace the batteries on your thermostat, which may be the solution to your problem. Periodically check for a blinking battery light or symbol on the thermostat to avoid problems in the long term. If it happens often, it could mean that replacing your thermostat is the best answer.

5. Analyze Your Blower

Head out to your unit to investigate thoroughly but carefully. If your unit is outdoors, you should be able to hear and see if the fan is on. If you can see or hear the fan moving in your unit and you feel air at the top, your blower is working, and you can rule it out as the problem with your unit. If you don’t see the blower moving or hear it working, be sure to mention that when you call an AC pro.

6. Check Fan and Compressor

While you’re outside, it’s a good time to check your fan and compressor. Inspect the fan motor thoroughly and look for any signs of damage. Other issues signaling an issue with your fan include:

• Slowly rotating blades.

• AC unit making a loud noise when the fan is on.

• Continuous rotation, even when the AC is off.

• No response to the AC turning on.

It’ll be tricky to pinpoint if the fan or capacitor is the problem because the capacitor powers the fan’s motor. So you’ll need to unscrew the condenser unit’s side panel to get a better look (make sure the breaker powering the AC is off before you attempt this). The capacitor is a cylindrical battery that has cables attached to it. If it’s swollen, then you’ve found the issue. If not, then the problem lies with your fan.

Fixing this is essential because it can affect your compressor’s lifespan if left to linger. AC compressor costs are more expensive than simply replacing a fan. That’s because the compressor’s job is to manage the refrigerant's airflow between the evaporator and condenser, and it can damage important and pricey machine elements like the AC capacitor when not in working order. The cost to replace an AC capacitor ranges from $70 to $350 for everything involved, so you’ll be looking at a lot of extra fees from just one damaged part.

7. Study Your Drain Line

After you’ve inspected your unit’s blower, look for any signs of leaking. If your coil is covered in ice, you see liquid near the coil, your machine is making a whistling sound, or there’s condensation on AC, the line is likely leaking refrigerant. We don’t recommend handling refrigerants on your own. Instead, call a pro to take it from here.

In the case of a leak, have a local air conditioning repair tech conduct a professional inspection.

8. Consider the Weather

Is your area experiencing a heatwave? When it’s hotter outside, older units have difficulty keeping up. If you’ve checked for everything else, it’s possible your unit is on the older side or isn’t big enough to handle the heat and the size of your home. Because your unit cannot run at its maximum efficiency, it may be time for you to upgrade the unit. 

After ruling out these issues, calling a local HVAC company can help identify the larger issue. On average, simple tune-up visits cost from $75 to $200, but extended problems can cost you up to $500.

Conroy Baltimore contributed to this piece.