Vacuuming down a mini split system is necessary before releasing the refrigerant.
It also is the main way a unit is tested for leaks.
The process is not difficult and easy enough for a DIYer with the right tools.
- Vacuum Pump
- HVAC Gauges
- Mini Split Adapter 5/16 to 1/4 Coupler
- Allen Keys
HVAC gauges and a vacuum pump are needed to set a mini split into a vacuum.
Alternatively a micron gauge can be used in place of HVAC gauges and do the same thing.
A vacuum pump simply evacuates all the air from the system placing it in a vacuum.
Most mini split units will also need an adapter to connect to the low pressure port.
Budget 410a Manifold Gauges on Amazon
ZENY Diagnostic A/C Manifold Gauge Set R134a Refrigeration Kit Brass Auto Serivice Kit 4FT w/Case, 1/4″ SAE Fittings
Mini Split Adapter 5/16 to 1/4 Coupler On Amazon
Wadoy R410a Adapter for Mini Split HVAC System 5/16″ Female Quick Couplers x 1/4″ Male Flare
Steps To Vacuum Down a Mini Split
- Hook the HVAC Gauges Blue hose to Low Pressure Port on outside condensing unit.
- Hook Center Yellow Hose to the Vacuum Pump.
- Turn On the vacuum Pump and open the valve on the HVAC Gauges Low Pressure Side (Blue).
- Let the pump run until it goes into a Vacuum, negative pressure.
- Let the pump run for at least 15-20 minutes and turn the pump off.
- Let the unit sit for some time 30 minutes or more and be sure the vacuum holds.
- If it holds the vacuum there there are no leaks and refrigerant can be released into the system.
- Using an Allen Key let the refrigerant into the system. Open both the high and low pressure valves on the outside condenser.
- Remove the Low Pressure Blue Hose from the unit as quickly as possible. A small amount of refrigerant will come out which will be minimal. This is necessary as to not break the vacuum.
Vacuuming down a mini split and releasing the refrigerant is not difficult and falls into the DIY category.
Of course if in-doubt be sure to call a professional.
There are some mini split systems that come set in a vacuum and do not require using gauges such as Mr Cool Mini Split Kit.
Most units will require the system be pumped down into a vacuum.
Here is a video I made installing a Senville mini split unit.
The vacuum process starts at roughly minute 10:50 in the video.