How Long To Vacuum Home AC System?

Your home air conditioning system needs regular maintenance. Dust and moisture may accumulate in the most sensitive parts of the AC system. Moisture in your AC system can cause many problems. You can use a vacuum pump to remove moisture and other debris from the system. Many people do not understand how long they need to vacuum their systems. Vacuuming your air conditioner for too long is undesirable. Similarly, you should not vacuum your system for a very short time.

How long should I vacuum my home AC system? 

You can vacuum your home AC system for about 15 to 20 minutes. You may also vacuum it for between 15 and 30 minutes. It all depends on the level of cleanliness of your AC system and its size. If you have a large system that has lots of moisture inside, you are likely to take about 45 minutes to remove all the moisture and other debris.

What Happens if I Vacuum My AC System for too Long?

The length of time that the evacuation process takes depends on many factors. Some of them are the level of system contamination, the size of the system, and the length of the vacuum hoses that you connect to the vacuum pumps.

If you vacuum your AC system for too long, the pressure on the gauge will go to a high negative reading. This may damage the components of your system and undermine its performance.

What Happens When I Vacuum my Home AC System for a Very Short Time?

If you vacuum your air conditioning system for a very short time, you will not have removed all the moisture and debris. The debris will remain inside the coils of the condenser in the external unit of the system. The debris will interfere with the way the condenser functions.

When the condenser does not function well, the entire system will struggle to cool your home during particularly hot days.

Also, if you vacuum the system for a very short time, moisture will remain inside its components, including the extension valves and compressor. The presence of water vapor inside the components reduces the refrigerant charge.

Why should I Vacuum my Home AC Unit?  

There are many reasons for vacuuming your air conditioning system. The reasons vary from the need to enhance the performance of the system to removing debris from the condenser.

Here are some of the most important reasons for vacuuming the system.

  1. As a general maintenance procedure – many homeowners largely forget about their ac units during the cool months. However, once the warm season kicks in, they remember the air conditioning system. You should regularly pull vacuum and carefully maintain your system during the cool months. This will ensure all the components are functioning well.
  2. To remove debris from the condenser – the condenser is in the unit of your air conditioning system that sits outside. The condenser has a series of tubes that help to cool the home. Because the condenser is outside your house, it is vulnerable to debris. Dust and other solid materials can easily enter the condenser. The dust interferes with the way the condenser cools your home during the hot days. Therefore, you should deep vacuum the condenser to free it of debris.
  3. To reduce energy consumption – the compressor of your system consumes a lot of energy when it overheats. Overheating occurs when there is moisture and air inside the compressor. Vacuuming the system gets rid of moisture and air. This saves you money.

What happens if you don’t pull a vacuum on an AC system?

When air and moisture accumulate in your AC system, they may cause serious damage. Proper evacuation of the system helps to remove all the air and moisture that may be trapped inside the unit. If you fail to deep vacuum your system, here are some of the things that may happen.

  1. Low refrigerant system pressure – The refrigeration lines need specific pressure levels for them to charge properly. When air is present in the AC system, it occupies that space set aside for the refrigerant. This reduces the pressure in the refrigeration systems of your unit.
  2. Decreased cooling capacity -This occurs because of a reduction in the performance of the condenser. The presence of air in the system reduces the ability of the condenser to function and the cooling capacity of the system.
  3. System failure – This occurs as a result of rust formation. Rust forms when water vapor that may be trapped inside the system reacts with the lubricant. The reaction produces acids such as hydrochloric acid. The acids can cause serious damage to the refrigeration system. Acid starts corroding the key components of the system. Over time, the entire AC system will stop functioning.

How to Vacuum a Home AC Unit with a Vacuum Pump

Pulling a vacuum entails removing contaminants from every component of the air conditioning system. Some of the components that usually accumulate contaminants include refrigerant lines, condensers, coils, and others.

Here is a step-by-step process of how to complete the vacuuming process once the system has been opened.

Adding Vacuum Oil to the Vacuum Pump

This should be the first step in the process. You need to set up your vacuum pump for the evacuation process. Before you do this, ensure that you add vacuum pump oil to the vacuum cleaner.

You can refer to the fill line to ensure that you put the correct amount of clean oil into the vacuum pump. Also, ensure you use the right type of vacuum pump oil.

Attaching the Gauges to the Ports

The gauge set comes in three color codes: red, blue, and yellow. You can use the color codes to understand how to connect your AC unit to the vacuum pump using the hose.

Use the red gauge and hose to connect to the high-pressure port of your AC unit. The high-pressure port is on the right-hand side. Use the blue gauge and hose to connect to the low-pressure port.

Use the yellow gauge to connect the red and blue gauges to the vacuum pump. When your gauges are closed, the pressure reading should be zero. You should use the valve that accesses the service to the refrigerant lines on your AC system.

Opening the Vacuum Pump

Once you are certain everything is correct, you can switch on the vacuum pump and allow it to begin the process. Let your vacuum start running then open the side vacuum gauge valve cores.

Doing this allows your vacuum to begin sucking the air out of your AC system. Let the vacuum hold at its full speed for about 15 minutes. This time is enough for the vacuum to complete the process called degassing.

The goal is to get a reading of less than 1,000 microns. Ideally, you should have a reading of 500 microns. A finishing vacuum of 500 microns is perfect even for a new installation air conditioning system.

This will ensure that the pump removes all the moisture that may be inside your system. You can finally switch off the vacuum pump and disconnect it from the AC system and hose.

How to Vacuum a Home AC Unit without a Vacuum Pump  

The refrigeration system of your air conditioning unit requires refrigerant and oil only. Any other substance, including air and moisture, is foreign.

These substances are non-condensables. They interfere with the way the compressor and condenser of your unit function. It may cause the entire system to fail or perform sub-optimally.

Using a vacuum is the best method of ensuring that the refrigerant in your system is free of any foreign substances. However, it is possible to clean the entire unit without using a vacuum pump.

The following is a detailed guide on how you can clean your unit without a vacuum pump.

Depress the Access Valve

Slowly reduce the pressure on the high-pressure access port of your AC unit. Ensure that the high-pressure and low-pressure port valves are secured in place. Depress the higher-pressure side to the lowest pressure point.

Charge the Low-Pressure Side

Carefully increase the pressure on the low-pressure side for at least 3 minutes. The goal is to ensure that both sides have equal pressure levels of about 14 psi.

Depress the High-Pressure Valve Again

Repeat the process while monitoring the pressure on both the low pressure and the high-pressure sides of the unit.

Charge the low-pressure side again to 14 psi and wait for three minutes as the pressure moves evenly between the two sides.

When the high-pressure side stops releasing any gas, it automatically shuts off. All the moisture and air would have been removed.

You can then recharge the system with the correct amount of refrigerant through the gauges.

How Long To Vacuum Home AC System FAQs 

System Evacuation is Considered Effective At

System evacuation is considered effective at 300 microns. This usually occurs after a 30-minute hold. If this is not achieved, there may be leakage. You will have to conduct a leak test.

How Many Microns for 410a?

500 microns or less are ideal for a 410a. This is applicable to a system that has poe oil. The decay holding for such a system should never be more than 1,000. If this occurs, there should be a problem with the pump or a leak.

Is 1000 Microns a Good Vacuum?

1000 microns is a good vacuum; however, you should focus on 500 microns. 500 microns is perfect for new installation as well as systems that have been running for a long time. You should achieve this ideal measure if you let your vacuum run for about 30 minutes maximum.

How Many Microns is a Good Vacuum?

500 microns is a good vacuum. This is ideal for you to have replaced a compressor. It is also low enough to ensure that you have removed the water vapor and air that may be inside your victim. However, some manufacturers insist that you should aim for 400 microns as the perfect one.

How Many Microns should a Vacuum Pump Pull?

A vacuum pump should pull 100 microns. This is enough to ensure that all the moisture in the components of your AC system, for example, is fully removed. You can verify this by attaching a micron gauge to your vacuum pump. In some instances, your pump should pull even 50 microns.

How Much Time do Manufacturers Suggest for Proper System Evacuation?

Manufacturers suggest that you spend a minimum of ten minutes for proper system evacuation. You can add one minute for every ton to allow for decay. It all depends on the size of the valves, the nature of the AC system, and other factors.

How Long to Vacuum Mini Split?

You can vacuum a mini split for about 20 minutes. This tie is enough for you to comfortably release the refrigerant and test the mini split for a leak. The process is not any different from what you can use to vacuum an AC system.

How Much Vacuum on AC System?

If there is no leak in your pump, you can vacuum an AC system for an average of 30 minutes. This time is enough to remove the moisture and air from inside your system. It is not advisable to vacuum the system for a very long time unless you are sure of the presence of a leak in the pump.

How Long should AC System Hold Vacuum?

The AC system should hold a vacuum for 30 minutes. This is the time that you need to let pass before closing the side valve. Use this measure to carry out a leak check. If the system pressure does not reach the ideal point, there must be a small leak.


You can vacuum your home air conditioning system for between 15 and 30 minutes. For the evacuation process to be successful, you need to understand how to maintain the right pressure. You can use a high-quality micron gauge to determine the pressure during the process.