• Home
  • |
  • Blog
  • |
  • AC Compressor Not Working but Fan is Running

AC Compressor Not Working but Fan is Running

As an Amazon Associate we earn from qualifying purchases. Learn More.

Your AC compressor is the heart of your air conditioning system and when it's not working  properly you'll definitely know. One common problem experienced by homeowners is when their AC compressor isn't working, but the fan is running. 

Repair man with hard hat

Get the Best Price on HVAC Repair and Installation

Call Now!

If your fan is running but your AC compressor isn't working there are several possible reasons why. This article will cover each and help you determine if you need to hire an HVAC professional to help you resolve your problem.

AC compressor fan

Signs Your AC Compressor Isn't Working

When your AC compressor isn't working you may notice that the circuit breaker frequently trips, or that the compressor shuts down completely.

Another common symptom is for the outdoor unit to shake and make noises. And of course, there's the situation where you'll find the fan running but the AC compressor not working.

Your air conditioning unit needs the compressor in order to deliver cool air to the inside of your house. The AC compressor is the heart of the system and is an expensive part to replace.

But not all compressor issues require replacement. Let's take a look at the most common reasons why your AC compressor isn't working but the fan is running.

Repairman working on HVAC Electrical

Why Your AC Compressor Isn't Working, But the Fan is Running

These are the top reasons why you'll find your AC compressor not working but the fan is running. Some issues can be resolved by yourself, especially if you're a DIY'er, and others should be fixed by an HVAC professional

Dirt and Debris

Your air conditioner doesn't just move air from one place to another, it also picks up particles of dust and debris in the process. The majority of the debris is collected by the filter, but if the filter isn't changed regularly the debris will build-up on the condensor coils.

Although, it's important to keep in mind that even regular filter changing won't totally protect your AC system. Dirt build-up is just something that happens overtime, but keeping your filter clean will make a huge difference.

When the air filter is dirty the airflow is significantly reduced, and without adequate airflow the evaporator coil can stop working. In fact, the entire AC system can shut down if your filter(s), condensor coil, or evaporator are dirty.

Even if your air conditioning system is still operating, when your air filter and condenser coil are dirty your compressor is required to work harder and it will eventually overheat.

If your compressor overheats, cross your fingers that it shuts down automatically before any damage was done. But if it didn't, you'll need to replace your compressor.

If this is your problem, you should be able to fix it yourself, unless of course, the compressor was damaged. Here's what you need to do: Replace your air filter, clean the condenser coils, and check and clear any obstructions in the supply vents.


This problem may not be your compressor at all! In fact, it could be as simple as a thermostat setting. Someone may have adjusted the themostat and you're expecting your AC to switch on.

However, the information coming from your thermostat is that the room is already at the correct temperature. In which case, the air conditioning system won't kick-in and neither will the compressor. 

If after adjusting your thermostat and your AC compressor still doesn't start, you may have a faulty thermostat which will need to be replaced by a technician. Although, this isn't the best outcome, it is far less expensive than replacing your compressor!

Electrical Issue

When the fan is running but the AC compressor isn't there's a good chance that electrical power isn't reaching the outside unit where the compressor is located - and since the inside unit has power, the fan is still operating.

First, check the circuit breaker to see if it has tripped or if there's a blown fuse. Then inspect the wiring between the inside and outside unit.

Unless you're comfortable working with electricity, it's typically best to contact a professional to help you troubleshoot an electrical problem.

Find Local HVAC Experts

Mismatched Units

Split systems have an indoor unit and an outdoor unit. These units are matched and designed to work together. Sometimes homeowners try to replace just one of the units to either save money or because they didn't understand how the system works.

This can be a costly mistake. If you recently replaced either your indoor or outdoor unit and your AC compressor fails to operate, there's a good chance that the units aren't properly matched. We highly recommend contacting an HVAC professional to help you determine your next move.

AC Capacitor and Starter Relay

A common problem with AC compressors is the starter relay and AC capacitor. These two components play a critical role in providing the compressor with the power it needs to operate.

The AC capacitor provides power to the compressor, outer fan, and the blower motor. The starter relay transmits the power to the compressor from the capacitors.

If you notice a humming sound and your AC compressor isn't working, it could be that the compressor is attempting to access the capacitor, only the capacitor is faulty.

If this is your problem, contact an HVAC professional. This is an inexpensive repair, but should be done by a qualified technician.

Dead Compressor

There's a lot of reasons why your compressor breaks down. It could be a refrigerant issue: Too much, not enough, or blocked lines. Or it could be that the compressor's oil lubricant was inadequate. It might even be an electrical issue such as the one discussed above.

Regardless, your compressor is dead and your AC isn't working, and unfortunately, your only choice is to replace your compressor. This can be an expensive job and should only be done by a professional.

Find Local HVAC Experts

Exceeded Service Life

Unfortunately, even the best air conditioning systems have a service life. If your system is over a decade old it may have reached the end of it's useful life.

Over time, the constant wear-and-tear causes internal components to breakdown and deteriorate. One of the ways a tired air conditioning system signals you is with troubles with the AC compressor. Although there may be other issues you'll notice as well.

As you might imagine, replacing your entire system isn't cheap. However, it'll run far more efficiently and you'll save money every month on your utility bills. 

Refrigeration Cycle

The Role of an AC Compressor

An AC compressor plays a very important role in getting cool air into your home. Most standard central AC configurations use what is called a split system. This is where part of the system is located inside the house and the other components are outside.

In a split AC system the compressor is housed in the outdoor unit. It's job is to move the refrigerant through the coils of the indoor and outdoor units. While circulating through the system, pressure changes occur to the refrigerant that allow the heat from inside your home to be carried and released outside. 

The gaseous refrigerant enters the AC compressor where the termperature is increased by compression, to a point where it changes into a high pressure gas.

The high pressure moves the refrigerant to the outdoor unit where it enters the condenser and releases it's heat. In the process the refrigerant changes into a liquid.

The liquid refrigerant travels to the indoor unit and enters the evaporator, where it once again becomes a gas. At this point it is ready to absorb the heat inside your house. Then it starts it's cycle again at the AC compressor.

The compressor is the driving force in your cooling system and without it, your air conditioner isn't able to deliver cool air. In other words, you may notice your AC compressor isn't working, but the fan may still be running.

Man with hard hat and work gloves

How to Keep Your AC Compressor Running

The average cost of replacing your home AC compressor is $1,200, so doing a little preventative maintenance can save you a lot of money in the long run. Here are three tips that can help keep your AC compressor working:

Clean the Condenser Coil - This is a simple task that will prolong the life of your AC compressor. You should also be able to do it yourself.

The condenser coil is where the heat is removed from the refrigerant. If your condenser coil isn't able to do this efficiently, your entire air conditioning system will need to work harder to keep your house cool. The condenser coil circles around the walls of the outside unit and resembles a screen-like grill.

There are two things to do in caring for your condenser coil. First, the thin, soft metal strips often bend and are not able to transfer heat as well as they should. If you find that they are bent, you can use a fin straightening tool to fix the problem.

Second, you can clean them. Grab your hose and use a spray-on condenser cleaner and you'll be able to remove the dirt and debris that's clogging them.

Monitor Refrigerant Levels - The refrigerant within your air conditioning system is used over and over. This is called a closed system, and if there are no leaks within the system, the refrigerant level should never change.

In many cases, the first sign of low refrigerant is when the AC is on but the air never seems to get cool. But it is possible that you'll see some fluid along the refrigerant lines. 

When your system isn't able to cool, the compressor will keep running as it attempts to drop the thermostat temperature. This places unnecessary wear-and-tear on the compressor and it will eventually wear out.

If you suspect that your refrigerant levels are low, you should contact a professional to check your lines for leaks and recharge the system. 

Regular Maintenance - The key to keeping your AC system operating efficiently is regular maintenance. Your compressor is designed to have a long service life, but you need to give it a little help, and that means conducting annual maintenance.

Some maintenance you can do yourself, and other jobs, you'll want to call a professional. Here are a few tasks you can do yourself:

  • Replace your filter every month during the cooling season.
  • Once a year, before the cooling season, remove the cover from the outdoor unit. It's very common for leaves and debris to collect inside. First, use a vacuum, and then thoroughly clean the housing.
  • Lubricate the fan.

We highly recommend having your AC system inspected by a professional once a year. He'll do a more thorough cleaning and inspection, check refrigerant levels, and ensure that everything is running as it should.

Consult with Local

HVAC Experts

Get Quotes from Qualified Local Contractors

Related Posts