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air conditioning repair

8 Helpful Air Conditioner Troubleshooting Tips for Homeowners

You think hockey players are tough? Sure. But if you want the real definition of rugged, look no further than your air conditioner. You shut it down in the fall. It sits outside in the snow, cold, rain, and ice for six to eight months. Then when the first hot day arrives, you flick the switch on the thermostat and it’s game on! It starts immediately pumping out cool air on-demand, without missing a beat.

However, like any mechanical device, air conditioning units are prone to wear and tear as they age, or after sitting for long periods. That’s why it’s important to keep your eyes and ears open for any issues as you put your AC back in action.

To help, we’ve shared some of the more common concerns, along with troubleshooting tips for your central air conditioner.

1. I can’t get my AC to turn on

First, make sure the thermostat is set to ‘Cool’ and the temperature setpoint is at your desired indoor temperature. If you’ve done this, and the thermostat temperature is above your set point but the A/C condenser is not coming on, it may be another issue.

Next, check your electrical panel to ensure the breaker hasn’t been flipped to the ‘Off’ position over the winter.

If the electrical panel breaker for the A/C is in the on position, the next step is to check the AC disconnect to make sure that it is set to the ‘ON’ position. This is a grey box that is generally located beside the AC condenser outside your home. There will either be a plug that needs to be pulled out, rotated 180 degrees, and then reinserted – or a breaker style switch that needs to be in the ‘ON’ position.

If you’ve checked the AC disconnect and your air conditioner is still not turning on, it could be faulty wiring or an issue with the thermostat. Don’t worry. An AC repair specialist can quickly diagnose and repair the problem.

2. There’s a funny smell when I turn on my AC

There could be several causes for this. A musty or dusty odor may simply indicate your furnace filter needs to be replaced. This can also occur if your ductwork and vents haven’t been professionally cleaned for a while.

If you notice a smoky smell it could be faulty wiring, which requires immediate attention. Shut off power to your furnace and air conditioner and call a professional immediately. If you have reason to believe there is an actual fire (steady smoke or you see a flame), call the fire department.

3. My air conditioner keeps turning off and on repeatedly

This is a common problem known as “short cycling”. It may be due to a faulty or an incorrectly set up thermostat. It can be caused by a clogged filter. Short cycling can occur if the AC unit installed is oversized for the home. It may also be due to an improperly charged AC system.

If this happens to you, shut off the AC at the thermostat and have a professional diagnose the problem right away. It’s generally an inexpensive repair. But if you don’t get it fixed, short cycling can damage the compressor, which is costly to replace.

4. My air conditioner is running continuously

Your air conditioner is meant to turn on when the air is warm and shut off when the home reaches the desired temperature. If you notice the AC is constantly running and your home is not reaching your desired indoor temperature (especially on days when it is not extremely hot out) you have a problem. This is hard on the motor and your energy bill.

troubleshooting air conditioner

This can be due to a low refrigerant charge (possibly caused by a slow refrigerant leak in the system), a frozen AC evaporator coil (the coil which is inside your furnace), a faulty blower motor, or condenser fan motor, or dirty/plugged AC condenser coils. A clogged furnace air filter can also be the culprit

In the event, your unit is running, yet struggling to keep your home cool, check your furnace filter and replace if needed. Then check your outdoor condenser. If you notice that the condenser coils are dirty and clogged with debris, you can clean with your garden hose (see photo). If you have eliminated both of these potential causes and your home still struggles to stay cool, a visit from a qualified AC repair specialist will be required.

5. My AC is on but isn’t blowing cool air

The whole point of having AC is to cool off. Again, it may just be a blocked furnace filter or a plugged condenser coil. Check those first.

If your AC condenser is running but there is no airflow from the vents in your home, then you may have an issue with your furnace blower motor. This will require a technician to diagnose.

If your AC condenser outside is running and you have airflow from your vents (but that air is not cool) the condenser may require a top-up of refrigerant. This is a simple fix that can be done as part of an air conditioner tune-up visit.

6. My AC is making unusual noises (Shut it off immediately)

Do you hear a loud squeal or a grinding noise? Squeals are generally caused by a worn compressor, condenser coil blower motor, or possibly the blower motor in your furnace. If you notice a grinding sound, turn off your unit immediately and call a professional. This is often a sign of a failing compressor or failing bearings in blower motors. You will want to get the issue diagnosed and repaired ASAP before any further damage occurs.

7. My air conditioning unit is leaking water inside my home

You may notice water on the floor of your basement near your furnace or in proximity to the refrigerant line set running from your furnace to the AC condenser outside.

This can be caused by improperly insulated AC line sets. The insulation on the larger diameter line can deteriorate over time. When the larger diameter copper line set is exposed to air in the home, condensation will form, drip and then collect on floors (or in ceilings if the line set is running through a finished ceiling). Improperly installed line sets with exposed copper can cause this too.

Moisture leaking from your furnace is often caused by a blockage in the condensate drain lines, which run from the in-furnace evaporator coil to floor drains or condensate pumps. Sometimes a faulty condensate pump can overflow. In certain circumstances, water near your furnace is a sign that a frozen AC evaporator coil inside the furnace that is thawing. Whatever the reason, it is best to call a professional to get to the source of the issue.

8. There is frost around my condenser coil

While not common, ice can form around the condenser coil (located in the center of the main unit outside of your home). This usually indicates your AC is low on refrigerant and needs a refrigerant top-up. It may also be caused by dirt or debris in the condenser coils. In rare instances, it can be a problem with the condenser blower motor.

Preparing for your appointment

Once you notice an issue, it is always recommended that you turn off your AC system, and leave it off until the service professional takes a look.

In cases where the evaporator coil, line set, or condenser coil is frozen, the ice will need to thaw before a technician can properly diagnose the issue. Again, turn off your AC. This will help the evaporator thaw quicker.

Notice an issue? Call a qualified AC repair specialist

Air conditioning units are extremely sensitive, requiring specialized tools and training. They should only be repaired by qualified professionals. Many of the air conditioning problems we mentioned will become worse over time and can result in more costly repairs if neglected.

At the first sign of a problem, call an AC repair specialist. The quicker you get the issue fixed, the sooner you can go back to enjoying a cool home.