Is Your AC Not Cooling Properly? Essential Checks to Make Before Calling a Technician

Before assuming your air conditioner needs a major repair, there are a few simple things homeowners can check that may help identify the issue early.

Start with your thermostat

Make sure it is set to Cool, not Heat or Fan Only. Then set the temperature at least 3 to 5 degrees lower than the current room temperature to see if the AC turns on.

Also check that the thermostat screen is working properly. If it is blank or fading, replace the batteries if it uses them. A weak battery can cause the thermostat to misread the temperature or stop communicating with the system.

If your thermostat is programmable or smart, review the schedule settings.

Sometimes the AC is not actually broken, it may simply be following an energy-saving schedule, away mode, or eco setting.

Make sure the thermostat is not being affected by heat from sunlight, lamps, TVs, appliances, or nearby electronics. If the thermostat senses extra heat, it may cause the AC to run longer than needed. If it is in a cooler spot, it may shut the system off too early.

You can also check if the fan setting is on Auto instead of On. Auto means the fan runs only when the AC is cooling. On means the fan may keep blowing air even when the outdoor unit is not actively cooling, which can make it feel like warm air is coming from the vents.

Next, check your air filter.

A dirty or clogged filter is one of the most common reasons an AC struggles to cool properly. When the filter is blocked, your system cannot move enough air through the home, which can make rooms feel warmer, increase energy usage, and put extra strain on the equipment.

If the filter looks grey, dusty, packed with debris, or light cannot pass through it easily, it is time to replace it. In most homes, filters should be checked monthly and replaced every 1 to 3 months, depending on usage, pets, dust, renovations, and how often the system runs.

Make sure the filter is installed in the correct direction. Most filters have an arrow on the side that shows airflow direction. If it is installed backwards, it can restrict airflow and reduce system performance.

Also, avoid using a filter that is too restrictive for your system. Some high-MERV filters can block airflow if the ductwork or equipment is not designed for them. A better filter is not always better if it makes your AC work harder.

A clogged filter can also cause the indoor coil to get too cold and freeze. If you see ice forming or notice weak airflow from the vents, turn the system off and check the filter before continuing to run the AC.

Take a quick look at your vents and registers.

Make sure supply vents are open and not blocked by furniture, rugs, curtains, boxes, or pet beds.

Even a partially blocked vent can reduce airflow and make certain rooms feel warmer than others.

Check the return air vents too. These are just as important because they pull air back into the system. If a return vent is blocked, your AC may struggle to circulate air properly through the home.

Look for weak airflow from the vents while the AC is running. If one room has much weaker airflow than the others, it could be caused by a blocked vent, closed damper, dirty filter, duct issue, or airflow imbalance.

Avoid closing too many vents in unused rooms. It may seem like it saves energy, but it can increase pressure inside the ductwork and make the system work harder.

Also, make sure vents are clean. Dust, pet hair, and debris around registers can restrict airflow and reduce indoor air quality. A quick vacuum around the vents can help your system breathe better.

Outside, check your condenser unit.

Your outdoor AC unit needs clear airflow to release heat from your home. If grass, leaves, dirt, branches, weeds, or debris are packed around the unit, it can reduce efficiency and make the system work harder.

Keep at least 2 feet of clearance around the condenser whenever possible. Trim back plants, remove loose debris, and avoid storing items too close to the unit.

Check the top of the condenser too. Leaves, sticks, patio furniture covers, or other debris can block airflow from leaving the unit properly.

If the coil looks dirty, dusty, or covered in cottonwood, grass clippings, or pollen, it may need to be cleaned. A dirty outdoor coil can cause poor cooling, higher energy bills, longer run times, and extra strain on the compressor.

Also, make sure the unit is sitting level and stable. If it has shifted, sunk, or tilted over time, it may affect drainage, refrigerant flow, or long-term performance.

Avoid using a pressure washer on the condenser. Too much pressure can bend the coil fins and reduce airflow. A gentle rinse with a garden hose may help remove light dirt, but heavy buildup should be cleaned by a professional.

If the outdoor unit is not turning on while the indoor fan is running, check the breaker and disconnect switch. If it keeps tripping, do not keep resetting it. That can point to an electrical or mechanical issue that should be inspected.

Also, watch for signs that it may be time to call a professional, such as:

•  Warm air coming from the vents

•  Unusual noises from the system

•  Water around the furnace or indoor unit

•  Repeated breaker trips

•  Ice forming again after thawing

•  AC running constantly but not cooling properly

Catching small problems early can often prevent bigger breakdowns during the hottest days of the year.

At Premium Home Services, we help homeowners in Hamilton, Grimsby, Halton, Niagara, and surrounding areas keep their cooling systems running safely and efficiently.

If your AC is not keeping up, send us a message or give us a call. We are happy to take a look and help you understand what is going on before it turns into a bigger problem.

Avoid the summer rush and get your

AC Breakdown Risk Report today!