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Guide On How To Vacuum AC System Without Pump

Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

Vacuuming your air conditioning system is important to ensure that it continues to run smoothly and provides the best possible results. But why is it so important? 

As you use the air conditioning system, moisture, and debris will collect inside it. Even a small amount can impact the performance of the system and make it less efficient.

If you let it build up then it could lead to serious issues and faults.

By vacuuming the system you can remove that moisture and ensure that these issues do not arise and it continues to function properly. 

If you want to know how to vacuum your air conditioning system, especially if you don’t have a pump, then you are in the right place.

We have put together this useful guide to help you. 

Keep reading to find out what steps you need to follow to vacuum your air conditioning system. 

Why Is It So Important To Vacuum Your AC System?

Air conditioning systems are made up of three main components – the air conditioning units, the air ducts, and the refrigerant lines.

The refrigerant lines are vital to the performance of the system.

They are designed for refrigerant and compressor oil to run through them, so if any other substances are present it can have a negative effect on the performance of the air conditioning system.

Other substances include water, which will inevitably build up in the system over time. 

The only way to remove this unwanted moisture from the air conditioning unit is to vacuum it.

The easiest way to do this is with a vacuum pump, but if you don’t have access to a vacuum pump then there are other methods you can use. 

What Problems Can Be Caused By Moisture Build Up?

There are lots of issues that can arise if moisture builds up in your air conditioning system and they vary in severity. Here are some of the most common ones:

  • Condenser Capacity – If the system is blocked with air and moisture then there is less room for the refrigerant. This reduces the system’s capacity to condense and cool. 
  • Refrigerant Charge – This is linked to the above issue. If there is less room for the refrigerant then less refrigerant will be charged, which reduces the overall efficiency of the system. 
  • Pressure and Temperature – If there is less refrigerant and a reduced condenser capacity then the temperature of the system will increase and the pressure within the system will rise. 
  • Energy Consumption – With a rise in temperature and pressure comes a rise in how much energy the system needs to operate. The Less efficient the system is, the more money it will cost you to run. 
  • Acid – When the moisture comes into contact with the lubricant in the system it forms acid. This acid builds and leads to rust and corrosion of the air conditioning system, causing faults, leaks, and failures. 

How To Vacuum Your AC System Without A Vacuum Pump

How To Vacuum Your AC System Without A Vacuum Pump

If you don’t have a vacuum pump then you can still do a good job of vacuuming your AC (see also ‘Fixing Your Clogged AC Drain Pipe Without A Fuss‘) system to remove the moisture. Here are some simple steps that you need to follow:

Step One – Depress The Access Valve

The first thing you need to do is depress the side access valve, which should take no more than five minutes.

Make sure that the compressor is installed and switched on and that the high and low pressure access valves are accessible. 

Find the side access pressure valve on your air conditioning and depress it, keeping a very close eye on the high pressure side.

Once the high pressure side has reached the same point as the low pressure side, turn the compressor off.

The access valve will now be depressed and you can move on to step two. 

Step Two – Charge The Low Pressure Side 

Once the access valve is depressed you can now charge the low pressure side to 14 psi.

Spend three or four minutes monitoring the pressure on both sides – high and low- to make sure that it balances out.

Once the pressure on both sides has equalized you can move on to step three. 

Step Three – Depress The Access Valve Again 

Once the pressure on both sides is equal, it is time to repeat step one. Turn on the compressor and depress the access valve as you did before.

However, this time you need to monitor the low pressure side rather than the high pressure side.

When it reaches the lowest point you can close the access valve on the high pressure side then switch off the compressor. 

Step Four – Charge The Low Pressure Side Again

Once again you will need to charge the low pressure side to approximately 14psi.

Wait for three to four minutes while you monitor the high pressure side and the low pressure side to ensure that they become equal. 

Step Five – Depress The Access Valve Once More

After you have charged the low pressure side for the second time, you need to depress the access valve for the third and final time.

If you have followed the other steps correctly then you should notice that the pressure will not drop as low as it did previously.

This is because the refrigerant and compressor oil have gradually been absorbed and released. 

As long as the high pressure side valve is not releasing any gas at this point then you can shut it off. 

Step Six – Charge The System With Refrigerant

By this point in the process, you should have cleared all the moisture from the air conditioning system. You are now ready to charge the system with refrigerant.

Make sure you use the right amount. Once you have done this, make sure the compressor is switched off, then you can start using your air conditioning system again. 


Vacuuming your air conditioning unit is very important to keep it running smoothly and to prevent issues from arising in the future.

The easiest way to do this is with a vacuum pump, but you can do it without one if you follow our guide. 

author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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