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How to choose right size A/C vacuum pump for auto ac

A/C vacuum pumps have a variety of uses for automotive air conditioning repair and automotive stores. The main purpose is to remove air and moisture from the automotive air conditioning system. Moisture is a serious threat to automotive air conditioning systems. Moisture passes through the refrigerant lines as a fine mist and crystallizes wherever it expands.

When the refrigerant is exposed to moisture, it becomes corrosive and causes problems with the air conditioning unit. You won't notice this damage until there are usage problems with the air conditioning system.


Knowing the role of A/C vacuum pumps and the importance of air conditioning maintenance, it is essential to have the right tools. Those who have worked in the air conditioning industry will be familiar with how different A/C systems operate and what kind of vacuum pump is what they need. However, those who are new to A/C vacuum pumps do not know what size pump they should buy.

What size ac vacuum pump do I need? what cfm vacuum pump do i need? There are many more questions you may want to ask. For someone who is new to vacuum pumps, it can be overwhelming.

So I decided to write this article to provide guidance. The type of vacuum pump you buy depends on your philosophy of buying the tool and how much you think you will use it.

First, you need to know what common types of vacuum pumps are available on the market.

Types of Vacuum Pumps

Diaphragm Pump

Does not use oil, does not emit any oil mist and is very quiet and durable. However, this type of pump can produce a medium vacuum level that usually does not exceed 83.5%.

Vacuum Generator

Requires an air compressor through a venturi to create vacuum, which is very noisy, but even with a large enough compressor can only produce 93.6% of vacuum. Without a large capacity tank, the vacuum level will fluctuate as the compressor moves in and out. All the wear and tear is basically borne by the air compressor and other more expensive equipment

Oil Filled Rotary Vane Pump

Requires oil and frequent oil changes, but produces the best vacuum (99.9%). No additional equipment is needed for long and stable operation. However, it is important to note that oil mist is generated when using cheap pumps or vacuum leakage systems.
Oil Filled Rotary Vane Pump

We think that oil filled rotary vane pump is the best choice. This pump is durable, inexpensive, easy to use and easily adaptable to vacuum presses.

Single Stage Vs. Two Stage

Oil filled rotary vane pumps are generally available in two types, single stage or two stage. Two-stage pumps have two rotors and two sets of vanes, the first stage produces vacuum and the second stage pumps on top of the first stage to create a better vacuum. Because the two-stage vacuum pump has a cleaning system for the second stage, it can produce a deeper vacuum than a single-pole pump.

However, a typical vacuum chamber and hose can produce a vacuum of 700-800 microns (the lower this value is, the better). A typical single stage pump produces a vacuum of 75 microns and a two stage pump produces a vacuum of 25 microns. In general 75 micron vacuum is sufficient for most situations. So, buying a single stage vacuum pump is a better choice, lower price and sufficient performance for use.

CFM (Cubic Feet per Minute)

CFM refers to how many cubic feet of free air the vacuum pump moves per minute. CFM drops significantly as vacuum is created. Once the vacuum chamber is reduced to a deep vacuum, CFM will be virtually unnecessary because the moving air is essentially no longer needed. When dealing with an identical air conditioning system, a larger CFM means getting to full vacuum faster.

So if you are on a tight budget, choosing a lower CFM vacuum pump would be a better choice. If you have more projects, then choosing a vacuum pump with high CFM can effectively improve your efficiency.

Maximum vacuum level

The HVAC industry uses microns as a common unit of measurement, so oil-filled rotary vane pumps usually show the vacuum level they can achieve in microns. The micron scale is a very precise scale for measuring vacuum and ranges from 0 microns (perfect vacuum) to 760000 microns (standard sea level no vacuum). Therefore, the lower the micron scale a vacuum pump can reach, the more perfect the vacuum produced.


Once you've determined what size air conditioning vacuum pump you need, it's just a matter of finding a reputable brand, and Orion Motor Tech vacuum pumps offer high performance at a low price, and perform very well when used with our AC gauge set.