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How To Vacuum AC System In Your Car – The DIY Process

ByTsukasa Azuma-October 23, 2023

Here is how to vacuum an AC system and how long to vacuum AC system. Read on, and get your facts straight about the DIY process that follows.

When you sit in your car hoping to get a cool breeze of air from the AC, and it doesn’t work, how do you feel? Frustrated and disappointed, right?

This is why you need to vacuum the AC system in your car. Wondering how to go about the process and how long does it take?

How To Vacuum An AC System – A Step-By-Step Process

So before going to know how long to vacuum AC system, let’s take a look at the way of vacuuming AC system. Here is an easy guide that you can do by yourself.

When you fail to vacuum the dust or moisture from within the AC system, it may deteriorate in terms of performance. Never wait for the problem to creep in, instead maintain the cleaning periodically for the AC to keep running. 

Let’s get deeper into the DIY process that can help you in implementing the cleaning process without much expenditure.

When you fail to vacuum the dust or moisture from within the AC system, it may deteriorate in terms of performance (Source: It still Runs)

1. Preparing And Identifying Service Ports

  • To begin with, park your car in a garage or anywhere, where the surface is flat. Do not start the car or the AC system within. 
  • Next, you need to wear gloves and a pair of protective glasses.
  • The next thing that would come in handy is a set of manifold gauges. Before you attach it, you need to make sure where the high and the low services ports lie.

The high-service port is larger than the lower counterpart. It is positioned amid the orifice tube or the expansion valve and the condenser. 

  • When you follow the AC’s compressor linkages and to the bottom of the car, a nozzle would be visible. 

This very nozzle is the low-side service port that is stuck amid the compressor and the evaporator.

  • Now the real work to vacuum the AC system car can start.

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2. Hooking Up The Manifold Gauge

Once the identification of the ports is done, you need to hook up the manifold gauge. These sets of gauges facilitate the linkage between the AC system and the low/high-pressure ports. 

Firstly, connect the vacuum pump’s hose to the low-pressure port present on the manifold gauge. This is the port that lies between the two gauges present on the gauge set.

Next, you need to connect the red-colored valve to the high-pressure port and the blue-colored valve to the lower one. It is the yellow valve that signifies the connection to the vacuum pump

One thing straight, remember to keep the valves in the closed position before connecting to the AC system.

Connect the vacuum pump’s hose to the low-pressure port present on the manifold gauge. (Source: AC Service Tech)

3. Making The Connections

So now, let’s move on to learn how to pull vacuum on car AC and how much vacuum to pull on auto ac system.

Get a hold on the right pressure port, and connect it to the gauge by merely lifting the connector ring in an upward direction and then pushing it in a downward direction. 

Next, you need to turn the red valve in the clockwise direction to activate the service valve, located beneath. Repeat the underlying step for the low port as well.

Once all the connections are secure and tight, it becomes essential to taunt the small valve which, in turn, activates the internal plunger. 

This plunger facilitates the actuation of the port valve to refrigerant lines. When concerned as to how to vacuum AC system without pump, one should know that it is possible but would not be that efficient.

4. The Vacuuming Action

Make sure the readings on both gauges are “zero.” Move on with connecting the other end of the yellow hose on the gauge to the vacuum pump. 

Now, turn the pump to the “ON” position. Vacuum pressure should be tracked and should reflect up to 27 Hg or aptly 29 inches. 

When concerned as to how long to vacuum AC system, you should know that it would take around 30-45 minutes. This is enough time to get rid of moisture and dust inside the AC system.

For effective vacuuming, open the low port’s valve of the gauge. Once, the tenure of vacuuming has ended; close the low-pressure valve and now you may switch off the pump. 

The gauge should be reading pressure around 27-29 inches. If the reading goes hay wired, there is a potential vacuum leak. Contrarily, if everything is fine, you can detach the vacuum pump car AC and place the hose in a refrigerant. 

Start your car, turn the AC on, and open the low-pressure valve that is present on the gauge in a slow manner. This step is undertaken to ensure a constant flow of refrigerant into the AC. 

Put the caps and the hood back on. And, you are done! You could also go through maintenance tips for the procedure for discharging AC at home.

Vacuum pressure should be tracked and should reflect up to 27 Hg or aptly 29 inches. (Source: Townlec)

How Long To Vacuum AC System?

So as many people wonder how long to vacuum AC system, the answer is 10-45 minutes. 

When it comes to the time to vacuum the AC system, you should know that usually, it would take around 30-45 minutes if there is no leak in the pump. This is enough time to get rid of moisture and dust inside the AC system

A vacuum of about 500 microns or 29.92 hg gauge pressure is needed for removing any moisture that may have entered the system along with the non-condensable gasses while it was open. 

Pulling a deep vacuum should be combined with the replacement of the AC receiver/drier or accumulator that will help to keep moisture inside the system under control.

Some people leave the vacuum for less than 30 minutes, some leave more than 30 minutes. Some even leave for 10 minutes only. There is a process that you can follow to optimize your time with the vacuum. 

First, pull the system down into a vacuum, shut off the valves on the gauges, and shut the vacuum pump off. Check to see if you have less than 1″ of vacuum in 10 minutes. 

If you do, you have not wasted 1/2 hour vacuuming down the system, just to tear it apart to fix a leak. If it passes the leak test, then vacuum down the system for 20-30 minutes and charge the system. 

The answer to the question of how long to vacuum AC system is 30-45 minutes. (Photo: OrionMotorTech)

Wrapping Up

Looking at the step-by-step procedure to vacuum AC and knowing how long to vacuum AC system, you would be all set to do it on your own. Remember to follow the instructions and feel proud when you effectively fix the vacuum system. 

Knowing how to do it will save you time and money by taking it to the expensive mechanic, meanwhile, you can do it by yourself.

Tsukasa Azuma is an awesome car blogger of Car From Japan. He owns a car repair shop at downtown Osaka, and he put all that experience to good use in his sharing posts. Tsukasa’s blog is one of the best resources for information about keeping your favorite imported car running smoothly. Moreover, because of being passionate to learn about the recent happenings in auto industry, he doesn’t only provide great car maintenance tips, he also always updates latest trends in among car brands and share them in his own interesting viewpoint.

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