Have you ever turned on your vehicle’s air conditioning only to find that the vents are blowing warm air? It is unsettling and annoying, yes? Such system malfunction is brought on by moisture or trapped air. Air that has been trapped in the air conditioning system must therefore be released. Therefore, you must vacuum the AC system to prevent a breakdown of the system.
Low and high air conditioning system sides draw a strong vacuum for at least 5 to 45 minutes when a vacuum pump is connected to both.
Step by Step Guide on How to Pull Vacuum on Car AC System

Before determining how long to vacuum a car AC system, let’s take a look at some simplified vacuuming techniques.
As previously mentioned, an air conditioning system’s performance will be affected if a vacuum isn’t drawn from it. I advise routinely vacuuming your air conditioning unit.
Do not wait until issues arise. Let’s go over every do-it-yourself step you need to take to remove the vacuum from the AC system.
Getting Started and Locating Low and High Service Ports
In your driveway or garage, place your car on a level surface. Check your local laws before vacuuming the AC on the driveway to prevent breaking any rules. Do not yet start the car or turn on the air conditioning.
Do not leave the house without your work gloves and safety glasses. Find the high and low service lines.
An H and an L are inscribed on the high service port and low service port, respectively. Search for the refrigerant lines. They follow the service ports on them and are fastened to the compressor. Not to worry about moving them. They cannot be swapped for one another. Go on to the following action.

Hook Up the Manifold Gauge
Next, hold up a gauge set after locating the service ports. Both the low and high service ports must be connected to the system using a manifold gauge. In addition to vacuuming and charging the system, you’ll use it.
Make sure the connections are “air tight” and the hose and fittings are free of leaks. The gauge’s valves must be in the closed position, so make sure they are.
The low-pressure side is represented by the blue hose, and the high-pressure side is represented by the red hose.
You’ll later recharge the system there, so the middle yellow hose needs to be connected to the vehicle’s air conditioning vacuum pump. Prior to attaching the gauge valves to the cooling system, close them.
Connect the Gauges to the Systems
Finding the appropriate vacuum to apply to the auto AC system is the next step. To the low-pressure service port, attach the blue gauge. To fix it, turn the knob down, attach the hose to the service port, and then release. Check to see if the hose snapped improperly by wriggling it.
Take the red hose from the manifold gauge and attach it to the high-pressure service port. To do it correctly, repeat the same procedure on the low-pressure line.
Both the low-pressure and high-pressure hoses’ gauge manifold hoses must be unlocked. Verify the manifold gauge’s gauge. Since there is no air in the system, it should be on “0.” The yellow line should then be attached to the vacuum pump for the car’s air conditioning.

The hose can be hand tight or barely more. A plier will suffice to complete the task for you. A seal there will do the trick. Other hose connections can be hand-tightened.
Go to a nearby garage to recycle any refrigerant that may be left in your air conditioning system. By venting Freon into the atmosphere, you don’t have to break any local laws. The atmosphere is adversely affected by these refrigerants. So, you ought to practice environmental responsibility.
Make sure the blue, red, and yellow lines are connected and open by checking them all at once. If you’re wondering whether it’s possible to vacuum an AC system without pumps, you can, but the results won’t be great. Let’s carry on to the next phase.
The Vacuuming Action
Set the vacuum pump to on. The manifold gauge’s gauge should be checked. The “0” position is where it belongs. The blue and red valves on the gauge’s sides should be opened. It should happen that the gauge needle drops below zero. You want the blue gauge to gradually decrease to 30 inches, so that should happen.
The red and blue valves on the manifold gauges should be closed and left closed for about an hour after the pump has run for about 30 minutes. The purpose of this step is to find any system leaks.
After the waiting period, if the blue gauge needle is still at 30, there is no leak in the system. If there is no leak, keep vacuuming for an additional 45 minutes. The gauge valves should be opened while the vacuum pump is running.

This will remove all the air and moisture from the system, leaving the interior completely dry. You can focus on something else while the pump works on its own.
When everything appears to be functioning fairly well after 45 minutes, close the gauge’s valves and turn off the vacuum pump.
The vacuuming process is complete. The air conditioner needs to be recharged with the suggested refrigerant as the next step.
What is the Purpose of Pulling a Vacuum
Here are the reasons you should vacuum your AC systems:
Eliminate Unwanted Contaminants
Does the air conditioner in a car require a vacuum? Particularly after replacing a damaged AC compressor or condenser, it is imperative to pull a vacuum on the air conditioning system. Unwanted contaminants should be removed from the air conditioning system by vacuuming it.
Keep the System in a Clean Environment
Evacuating air and moisture from cooling and refrigeration systems is a necessary step in drawing vacuum from the system. To remove harsh substances from an air conditioning system, a vacuum must be pulled. Moreover, to guarantee a pristine environment for the system to operate in.
To Prevent System Premature Breakdown
A mechanical failure of the compressor and expansion valves could result from failing to vacuum your air conditioning system. Refrigerant line restrictions, decreased efficiency, premature corrosion, and eventual system failure are among the other problems it will project.
You should regularly vacuum the system to protect it from the problems mentioned above. Especially when recharging the system’s refrigerant after installing a new AC component.
FAQs
How Long Should You Pull a Vacuum on a Car AC System?
How long does it take to remove a vacuum from a car AC system now that we know how to do it? In an AC system without a leak, it typically takes 45 to 1 hour to draw a vacuum. Enough time has passed for the system to clear air and moisture.
Replace the AC receiver or accumulator when vacuuming up deep moisture. As a result, moisture levels will be controlled.
Can You Pull a Vacuum on Just the Low Side?
Of course, the low-pressure line is the only one from which you can draw vacuum. The cooling system is always on. Orifice tubes, one of its parts, limit but do not completely stop the flow of refrigerant. Only the low side can be evacuated to remove the vacuum.
Does Pulling a Vacuum Remove Refrigerant?
Refrigerants are removed by drawing vacuum from your cooling system. However, only remove vacuum after recycling the refrigerant.
The vacuum pump will be harmed if it is used to remove refrigerants. They are only intended for moisture removal. Do not attempt to remove refrigerant using a vacuum pump. Purchase a refrigerant recovery device in its place.