How To Vacuum A Mini Split and Remove Refrigerant

Any amount of harmful exposure can exponentially affect the performance of your air conditioner and lead to long-term problems.

The solution to that is vacuuming and refrigerant removal, which allows you to get rid of any moisture from your AC system. Read this guide to learn how to vacuum a mini-split.

How Do You Vacuum A Mini Split AC? (DIY Guide)

If you do not vacuum your air conditioning system, particularly after service or installation, you may not enjoy the optimal performance of your system.

Tools Needed

Step by Step Guide

  1. Make sure that both the High (Red) and Low (Blue) valves are shut off in your AC gauge.
  2. Attach the HVAC gauge’s blue hose onto the low-pressure port on the condensing unit outside (it is typically your device’s only port)
  3. Hook the yellow hose in the center into your vacuum pump
  4. Turn your vacuum pump on and open the HVAC gauge’s (blue colored) low-pressure part
  5. Allow your pump to run until it goes in a negative pressure indicating a vacuum
  6. Run the pump for a minimum of fifteen to twenty minutes or longer, and then switch off your vacuum pump
  7. Let your unit rest for twenty to thirty minutes and ensure the vacuum stays in place
  8. If there is a vacuum, then there are no leakages, and it will release the refrigerant into the system
  9. Via the Allen Key, allow your refrigerant to enter your air conditioning system. Then, open both low and high-pressure valves on the external condenser. Opening it out will take multiple turns
  10. Remove the low-pressure hose from your device quickly. Some refrigerant may leak, but that is all, and it is required to break the vacuum
How to Vacuum a Mini Split AC

What Happens If You Don’t Vacuum The AC Before Releasing The Refrigerant?

If you do not vacuum your mini-split AC before adding a refrigerant, it may lower performance and cause severe damage. Because via mini-split evacuation and vacuuming, you ensure that there is no air and moisture inside the system.

Following are specific problems that might happen if you do not vacuum your mini-split:

Reduction In Condenser Capacity

Because of the air inside your refrigerant coil, the excessive volume will be covered by air particles, which reduces the refrigerant volume. Subsequently, the cooling capacity will also decrease.

Acid Formation

We all know that the refrigerant coil contains refrigerant. Not vacuuming means moisture won’t be removed. When both moisture and lubricant are present, a chemical reaction happens, causing acid formation that leads to rust formation on your air conditioner’s internal parts.

Higher Energy Consumption With Low Cooling

When there is low refrigerant capacity, the pressure in the condenser will increase. This increases compressor load because of which the cooling rate decreases while increasing energy consumption. Due to this, your compressor will overheat, ultimately resulting in motor winding failure and high-power consumption.

Why Is Vacuuming A Mini Split Necessary?

You must vacuum your air conditioning system to eliminate any moisture or air which might ultimately damage your system. Moisture in your air conditioning system is a severe issue since it lowers your AC system’s performance, and water condensation may cause your AC system to freeze.

Condensed water particles will corrode your air conditioning system and result in long-term damage. Forming a deep enough vacuum to boil the moisture away via a vacuum pump regularly is a low-cost and effective method of maintaining the health of your air conditioning system. You can purchase or rent pumps if you are not looking to make a long-term investment.

Common Reasons Why Refrigerant Needs To Be Removed?

Air conditioning units contain refrigerant inside their upper coils. The air conditioning components send refrigerant outside where the fan blows hot air over coils and exhausts it to the exterior. As the refrigerant absorbs indoor heat, it shifts from low-pressure gas to liquid that is high-pressure.

Your air conditioner refrigerant will then cool it down and revert it to a low-pressure gas. There is another fan present inside the home which blasts air over cold coils to disperse the resultant cold air all over the building, and the cycle reoccurs.

It is necessary to remove your refrigerant before performing the mini-split vacuum procedure. Otherwise, it might result in condensation and rusting of your internal air conditioning unit. However, remember that if your air conditioning unit contains Freon as refrigerant, it is better to call a certified professional since the EPA necessitates that Freon removal must only be handled by a Section 608 certified professional.

Why Refrigerant Needs To Be Removed

People Also Ask (FAQ)

And here are common vacuuming mini split AC questions people usually ask.

Does vacuuming AC remove oil?

When you empty your air conditioning system, you also get rid of any miscible oil. Vacuuming the system (for 30 minutes) will not remove all the oil. Hence, there will still be some of it left in the lower spots of your drier, condenser, and evaporator.

How long should an AC vacuum hold?

If you’re running the vacuum pump for a half-hour, shut the low side valve and switch it off. Your system should hold at 28 to 29 inches. There is probably a large leak if it never reaches 28-29.

How can I vacuum my AC without a vacuum pump?

Connect a discharge pipe with the outdoor and open suction pipe and discharge the L key valve while closing the suction L key valve.

Now turn the outdoor unit on and air will travel from the discharge pipe and come out of a suction pipe. After 5-7 minutes, connect the suction pipe and turn off the outdoor unit to create a vacuum.

How much does it cost for an HVAC pro to vacuum a mini-split AC?

The average cost to install a mini-split goes around $800 to $2,500 based on the tonnage. However, having an HVAC pro vacuum your mini-split will cost you about $200-$400.


It is essential to perform mini-split evacuation from time to time, preferably during the transition from winter to summer, to maintain optimum performance of your air conditioning mini-split unit.

Hopefully, this guide was able to help you understand the ins and outs of how to vacuum down a split system.

Josh Mitchell

Josh Mitchell

My name is Josh and I am obsessed with DIY and improving my family home. HVAC topics can be tricky for homeowners so I decided to share my knowledge on the subject. When I am not working on DIY projects, you can find me at the beach or my local coffee shop.