AC Compressor Not Working? Troubleshooting Steps and Common Causes

When it comes to costly repairs, AC compressor issues can quickly add up. Before you worry about getting a compressor replacement, it’s important to figure out whether this is the actual issue. Once you have the problem diagnosed, you can decide if it makes more sense to repair or replace your cooling system.

To learn more about things you can check on your own and when you should call for help, read on.

What an AC Compressor Problem Usually Looks Like

If your compressor is the problem, you’ll likely notice warm airflow, poor performance, unusual noises, and higher-than-normal energy bills. In particular, pay attention to any loud banging, clanking, or rattling noises. There may also be buzzing or vibration on startup.

Because of how much energy a faulty or overheated compressor can pull, it’s common for the breaker to trip when the compressor is starting to fail. This increased energy draw can also trip the breaker, so note any frequent breaker trips.

Once you’ve noticed these signs of potential issues, the next step is using safe DIY checks to troubleshoot and detect the root cause. If these basic tips aren’t enough to resolve the issue, then you’ll need to schedule a professional heating, ventilation, and air conditioning (HVAC) appointment.

Start With Safe Troubleshooting Steps

When your AC suddenly makes unusual noises or stops working, you don’t have to panic. Instead, start with the following basic troubleshooting steps.

Check Thermostat, Power, and Breaker Status

First, you should see if something is wrong with your system’s controls. Check to make sure the thermostat is set to cooling mode and the temperature is cooler than your room temperature. 

If your air conditioner doesn’t kick on, look at the breaker position. A tripped breaker can cause your unit to stop working. If this is the case, turn the breaker all the way off. Then, turn it back on. 

While resetting the breaker often works, you should only do this once. Breakers that trip repeatedly need to be inspected by a professional because there is an underlying electrical or mechanical issue causing the repeated tripping. 

Check Airflow and Outdoor Unit Condition

The next step is to check your airflow and outdoor unit. When a filter becomes dirty, it can reduce airflow and cause the evaporator coil to freeze. Because this makes the compressor work harder, it can cause the compressor to fail. 

You should also inspect your outdoor condenser unit for airflow blockages. If it becomes blocked by plants or debris, the resulting airflow problem can end up affecting your AC compressor.

What Not To Do

Your AC is a complex machine. For your safety, you should never handle any wiring or capacitor repairs yourself. The capacitor is responsible for storing huge amounts of energy to start the compressor, so mishandling this component can cause electrocution.

Common Reasons an AC Compressor Stops Working

There are a few common reasons why an AC compressor may stop working suddenly.

Power Supply or Breaker Issue

When there are issues with your electrical supply or breaker, it can impact the AC compressor. In particular, electrical interruptions, failing switches, and repeated breaker trips are all signs that this could be the problem. Because electrical components are involved, you should leave these repairs to the professionals.

Failed Capacitor, Contactor, or Relay

Whenever a capacitor, relay, or contactor isn’t working right, it stops the compressor from starting up. Again, this is another repair that must be handled by licensed technicians.

Thermostat or Control Problem

If the thermostat isn’t communicating properly, it may not trigger the compressor to start up. For example, you may be dealing with a bad signal, low voltage, or incorrect settings. While you can check the thermostat settings on your own, any other repairs will necessitate a service call.

Low Refrigerant or Refrigerant Leak

When your refrigerant starts to leak, the levels can decline. This can cause heat to build up, and it results in more stress on your compressor. You’ll need a technician to find and fix the leak because, by law, refrigerants can only be handled by someone who has the appropriate certification.

Internal Compressor Damage or Age-Related Failure

If the internal compressor is damaged or fails due to age, the repair costs can quickly add up. Especially in older units, it is often better to replace the AC instead of performing an expensive repair.

What the Symptoms Can Tell You

You can get a better idea about whether you have a compressor problem by paying attention to a few common symptoms. The type of noise can also help you figure out if your AC needs to be repaired or if it is completely dead.

Clicking, Buzzing, or Humming

The sounds you hear can help you differentiate different kinds of AC problems. If you hear clicking, humming, or buzzing, it means your AC is trying to start and can’t. When there are no noises present at all, your compressor is likely dead.

Warm Air, Short Cycling, or Outdoor Unit Silence

When your AC isn’t functioning at its best, you may notice short cycling and warm air. Short cycling often occurs because of airflow problems, oversized ACs, and safety shutoffs. Warm air may stem from airflow problems or low refrigerant. A completely silent outdoor unit may be due to a faulty breaker, failed capacitor, contactor issue, or safety switch-related problem.

These types of symptoms are important because they help you narrow down the problem. Even if you can’t safely fix the issue on your own, this information will help the HVAC technician diagnose what is wrong with your unit.

When Troubleshooting Should Stop, and Repair Should Start

While there are some problems you can fix on your own, you should never put your health or the health of your AC at risk.

Electrical or Safety Red Flags

Electrical problems should never be dealt with on your own. Burned odors, visible signs of wire damage, and repeatedly tripped breakers are all indications that you should immediately stop working with your AC and call for help.

Signs the Compressor May Be Failing Internally

If the root cause of your AC malfunction is the compressor, you won’t be able to fix it on your own. You should schedule professional AC repairs as soon as you notice the following symptoms.

• Loud noises, like clanking, banging, and rattling sounds
• Overheating
• Issues starting up
• Age-related decline

Repair Versus Replacement: When the Conversation Changes

Our HVAC technicians will carefully evaluate your situation to determine which solution will work best for your short-term and long-term needs. The age of your unit, the extent of the repairs, and your future goals will determine whether a repair or replacement makes more sense.

When Repair Still Makes Sense

Repairs make sense when we only need to replace an isolated part, such as your contactor or capacitor. If you have a relatively new AC that has had minimal repairs, performing a repair is likely a good choice.

When Replacement Is Worth Discussing

Once units get older, they can start to fail. If you have an aging system or have experienced a significant drop in your AC’s energy efficiency, it is likely time to get it replaced. Repeated repairs are another indicator that your unit is starting to fail and needs a replacement.

Compressors are known for being one of the more expensive repairs. If your compressor is damaged and must be replaced, it may make more sense to replace the entire AC instead.

FAQs

Can an AC compressor stop working because of a dirty filter?

Yes, it can. When the air filter is clogged, it can restrict airflow and cause the evaporator coil to freeze. As the coil freezes, it forces the compressor to work harder in order to cool your home. Eventually, this can result in the compressor breaking down.

Why is my AC compressor not turning on, but the fan is running?

If this occurs, it is likely due to a failed capacitor. It could also be due to control problems, such as when the AC is set to fan mode only. Additionally, a tripped breaker can cause this to happen. While you can try resetting the breaker and adjusting your thermostat settings on your own, capacitors should only be handled by a licensed technician.

Is it safe to keep resetting the breaker on my AC?

No, it is not. If the breaker keeps tripping, it means that there is an underlying problem with your AC that needs to be addressed. Continuing to reset the breaker can end up damaging your unit.

Does a bad compressor mean I need a new air conditioner?

It depends. If your AC is already 10 years old or older and has a history of needing repairs, it’s probably time to get a new one. When our technicians come out, we’ll compare the cost of repairs to the cost of a replacement. Then, we’ll calculate the estimated lifespan left on your AC to help you determine which option makes more sense.

Diagnose Your AC Compressor Issues

With summer just around the corner, you can’t afford to have your AC stop working. If you think that your compressor is not working anymore, Rogue Valley Heating, Cooling & Electrical can help. 

Ready to schedule your AC diagnostics and repairs in time for summer? Give Rogue Valley a call today.