A bad compressor in an air conditioner or heat pump is one of the worst issues an HVAC system can have. That’s because the compressor is the most important component in either of these units. If the compressor completely fails, you’ll no longer be able to cool or heat your home. Some signs of a bad compressor are fairly easy to spot and are something you’ll realize almost immediately. Others are more difficult since they can be related to other issues.
Understanding the Role of an HVAC Compressor
The compressor in an AC or heat pump serves two essential roles. It’s responsible for pumping refrigerant through the system so that it flows to the evaporator coil before eventually flowing back to the unit outside. Also, it compresses the refrigerant, which is an essential step in the cooling cycle.
As the system runs, the refrigerant continually goes through a cycle where it changes from a cold, low-pressure liquid into a hot, high-pressure gas. This process is only possible because the compressor compresses the refrigerant so that its pressure greatly increases, and it immediately boils and turns into a gas. The refrigerant starts out as a cold liquid, which allows it to capture heat from the air inside the house as it moves through the copper tubes in the evaporator coil. It then travels back outside where it gets compressed before flowing through the tubes in the condenser coil. Compressing the refrigerant is essential since it causes it to become much hotter than the air outside. This allows all of the heat to be released. The refrigerant then changes back into a cold liquid.
This same process is also what allows heat pumps to capture heat from the outside and transfer it into the building. The only difference is that it works in reverse, meaning the refrigerant flows in the opposite direction and gets compressed before being pumped inside.
AC or Heat Pump Won’t Turn On
If the compressor completely fails, it will result in your AC or heat pump not turning on. This can happen for a variety of other reasons, too, such as a bad contactor relay switch or start capacitor. It could also mean there’s an electrical issue preventing power from flowing to the unit or even an issue with the thermostat not signaling the unit to turn on as it should. The only way to know for certain whether you’re dealing with a failed compressor is to have a technician perform an inspection and diagnostic assessment.
Unit Keeps Tripping the Circuit Breaker
There are really only two main reasons why an HVAC system will frequently trip the circuit breaker. The first is that there is some type of electrical fault somewhere in the system, like a loose or damaged wire. In this case, the system short circuits and causes a power surge that trips the breaker.
The second reason is that the compressor motor, the condenser fan motor or the blower motor is starting to give out. It takes a massive amount of power for all of an HVAC system’s motors to start. In fact, they usually draw around three to five times as much power when starting up compared to how much they draw when fully running. When any of these motors start to fail, they often have issues where they can’t start up easily. This can sometimes lead to the motor drawing much more power than it should in an effort to start, causing the breaker to trip.
Unit Vibrates, Hums or Buzzes When It Turns On
If you hear your outdoor HVAC unit vibrating excessively or making a loud humming or buzzing sound when it starts up, it’s almost always a sign the compressor is failing. These sounds result from the compressor motor making a “hard start.” A hard start means that the compressor motor is struggling to turn on, which often causes it to vibrate and hum or buzz.
There may also be times when you hear a humming or buzzing sound when the unit tries to start but fails to turn on. In this case, it usually means that the unit’s start capacitor is bad. A start capacitor is essentially like a large battery that releases a powerful jolt of electricity to help the compressor motor and condenser fan motor start up more easily. Without this extra power, the motors often won’t be able to start up on their own. They can also end up overheating when they try to start and potentially burn out. In this situation, shut your HVAC system off immediately.
Unit Is Ticking, Rumbling or Rattling
A ticking noise when the unit turns on and off also usually indicates that the compressor is failing and having issues turning on and off smoothly. Rumbling and rattling noises instead typically indicate that the mounts that hold the compressor motor in place have come loose. This results in the motor shaking and moving around inside the sealed compressor.
Warm Air Blowing Out of Your Vents
Another potential sign that your compressor is failing is if your HVAC system is blowing warm air when in cooling mode. The same is true if your heat pump system starts blowing cold air when running in heating mode. The reason these issues can happen is that a failing compressor often can’t pump the refrigerant through the system as it should. A refrigerant leak or a frozen evaporator coil can also cause the system to blow warm air, which is why you’ll need a technician to diagnose the specific issue.
Moisture Puddling Around the Unit
Condensation can sometimes form within an outdoor HVAC unit and cause water to puddle up underneath and around it. Moisture can also be a sign that refrigerant is leaking out of the compressor, the condenser coil or one of the copper lines. These latter issues are quite serious and something that requires immediate attention from a professional.
Options for Dealing With a Bad Compressor
When dealing with a bad compressor, you have one of two options: replace the compressor or replace the entire unit. Compressors are fully sealed, which means there is no way for a technician to repair them. Unfortunately, replacing a compressor is extremely expensive and time-consuming and will usually cost well in excess of $1,000. This is why most people just opt to install a new AC or heat pump when dealing with a bad compressor. Nonetheless, it can be worth it just to replace the compressor if the unit is fairly new. It’s also usually worth it if the unit is under warranty and the compressor failed because it was defective. In this case, the manufacturer will provide a free replacement compressor, and you’ll only need to pay the labor fees for installing it.
If you suspect your compressor is bad or you need any other HVAC repairs, you can trust the experts at Meade’s Heating and Air. As one of the leading HVAC companies in Sterling and Northern Virginia, we have what it takes to professionally handle all of your home comfort needs. Whether you need an inspection, repairs, maintenance or a new installation, give us a call to ensure the work gets done correctly. Be sure to rely on our emergency HVAC services when things go south!
