How Do I Know if My AC Unit is Dying? | Direct Energy Blog

How Do I Know if My AC Unit is Dying?

When your air conditioning unit starts acting up, you face a critical and potentially expensive decision: Do you call in a repair person, attempt to fix the appliance yourself or start the search for a replacement? Read on for tips to help diagnose the cause of your AC issues and guidance on when it might be worthwhile to attempt a fix versus purchasing a new unit.

Troubleshooting Your Air Conditioner

Let’s begin by assuming that your AC was running well until it abruptly started having problems. Start with this basic troubleshooting routine to diagnose some of the most common issues you could be experiencing:

  • Double check your thermostat settings to be sure that the unit is set to run.
  • Check the fuse box and look for any tripped circuit breakers, as sometimes voltage spikes can cause them to trip. In most instances, there will be one breaker for the inside unit that controls the blower and another breaker for the outside condenser unit. If you find your AC system breakers have tripped, go to your thermostat and turn the system off.
  • Next, turn on the breakers. Return to your thermostat and turn on the blower fan only. If it runs normally, that’s a good sign the problem might be elsewhere.
  • Turn the system to cool and observe the outside condenser unit. If the fan spins up and the system begins functioning normally, then everything should be ok.
  • If at any time one of the breakers trips again, that means there’s a fault somewhere in that circuit and you should seriously consider having a trained professional look it over.

Diagnosing Other Air Conditioner Problems

If an initial investigation doesn’t reveal the problem with your air conditioner, consider the following symptoms and the clues they offer toward the root cause of the issue, which in turn will inform your decision on whether your money is best spent repairing or replacing the unit.

The system is running but there’s little or no air blowing, or the blower makes a higher than normal whine.

  • Check the air filter to see if it’s completely clogged with dirt. If it is, replace it.
  • Check the return vents to make sure none of them are blocked off by furniture or carpets. Air needs to flow freely into these.
  • Check the evaporator coils where the refrigerant from the outside condenser cools the air from the blower. These coils can collect lots of fine dust over the years and once in a while they need to be cleaned off. Turn off the system and remove the access panel. The evaporator coils are in an A-frame. Be very careful not to bend or damage the coils or any of the connections. Gently use a dust wand vacuum attachment to remove the dust, then wipe off any clogs of dust with a cloth and mild spray cleaner. For stubborn grime, you can get foaming AC evaporator coil cleaner. Lastly, replace access the panel.
  • Check the blower. Is the motor running? Usually, you can hear it when you’re standing right next to it without opening any access panels. If the blower isn’t running, turn the system off and check for loose wiring connections leading to the motor. Vibration from the motor can sometimes shake connections loose.

 The blower motor squeaks or squeals in operation. It also smells hot.

  • Turn off the AC system and remove any access panels. Try to turn the motor’s shaft by hand. If the shaft is hard to turn, then the bearings need to be oiled. Blower motor bearings are surrounded by felt pads soaked in machine oil which, after 5 or 6 years of continual use, can dry out. The oil ports for the bearings are located at either end of the motor shaft. It can be a messy and time-consuming job but it’s cheaper than buying a new motor. You’ll also want to take a little extra time to clean all the dust and fuzz that falls out from the blower fan.
  • Check the blower fan belt. Because some blower systems are belt-driven, the belts can wear out or stretch over time and need to be replaced.

The system is running and the blower is working, but the air is not cold.

  • Is the outside condenser unit running? If not, check the fuse box to make sure the breaker hasn’t tripped. If air is unable to freely flow all around the outside condenser, the unit will pull more current trying to cool itself until it overheats and trips the breaker.
  • Remove any leaves, brush or vines from around the outside condenser that might hinder air circulation.
  • Clean the condenser coil fins. Dirt and dust clogging the cooling fins can ruin air flow blown by the condenser fan to cool the coils. Every so often throughout summer, wash out the cooling coils with a hose. Be sure to turn off the air conditioning beforehand.
  • Look through the fan grate into the condenser. Keep an eye out for frayed or loose wires which could lead to dangerous electrical shorts and fires. Frayed wiring can be a sign of gnawing rodents or other pests that might nest inside, which is a good reason to never cover the unit in winter. Turn off the system and remove any branches or debris that have fallen inside. Damaged wiring should be repaired by a trained professional.
  • The fan should spin freely. With the system shut down, use a pencil or long screwdriver to nudge one of the fan blades. If the blades don’t move easily, there may be something wrong with the motor requiring replacement. Again, call in a professional.

 The outside condenser unit buzzes noisily. The fan turns slowly or not at all.

  • This is a sign that the power capacitor may be going bad. A normal capacitor is a cylinder with flat ends. On one end, there are a pair of wire contacts. Capacitors are similar to batteries in that they store electricity, but only for short periods of time. Over time, capacitors can degrade and bulge at the ends or start leaking, which is when they need to be replaced.
  • Investigate the capacitor by turning off the power supply or circuit breaker to the condenser. Next, find and remove the access panel. Locate the biggest capacitor and see if it’s bulgy or leaking. Under no circumstances should you touch the wire connectors or contacts, as these big power capacitors can hold a high voltage charge that is dangerous enough to badly burn or even kill you. Replacement should only be done by a qualified, licensed repair technician.

The outside condenser unit buzzes noisily but the fan is spinning. No cold air.

  • This is one indication of a bad compressor, especially if the unit is overgrown and dirty. Another indication is that the fan spins up but there’s a noisy clattering or grinding noise coming from the compressor motor. Again, it’s time to call in a professional.

The system is running, and blower and outside condenser seem to be running fine, but no cold air.

  • Coolant has probably leaked from the system. The most common places for leaks are where the coolant circulation tubing connects to the inside heat exchanger or the outside condenser. These connections are not soldered like copper plumbing. They are brazed, which is usually done with an acetylene torch. Common causes for leaks are too much vibration or dogs urinating on a unit with aluminum cooling coils.

Taking into Account Parts & Refrigerant Availability

In addition to the outright cost of repair vs. replacement for your air conditioner, another factor to take into account is the ability to acquire replacement parts and refrigerant for older units. In 2010, production and importation of HCFC-22 (R-22) refrigerant was banned. All HVAC systems manufactured after 2009 must use the new environmentally-friendly refrigerant, R-410A. However, pre-2010 HVAC systems can’t use R-410A due to changes in compressor design and other requirements.

One consequence of this change is that some major replacement parts for pre-2010 HVAC systems are harder to find and thus cost more, because fewer and fewer old systems will remain in service as time goes on so there’s no reason for manufacturers to make parts.

What’s more, while R-22 refrigerant is still available, it is no longer produced in the United States, nor can it be imported. By 2020, only recycled, reclaimed, or previously produced HCFC-22 can be used. Consequently the price will likely increase drastically.

Therefore, if your home’s HVAC system is a pre-2010 system that uses R-22, you should seriously evaluate the pros and cons of fixing it if you are faced with a major repair, such as leaking refrigerant, burned out motors or compressors, or replacing coils. Putting in a newer, more efficient system sooner rather than later may wind up saving you more money as your older system ages and R-22 system repair costs continue to increase. In addition, a new energy efficient HVAC system could save you save 20% to 40% on your cooling energy costs.