How Long to Pull Vacuum on Car Ac System

Last Updated on June 23, 2023 by Ryan

Pulling a vacuum on an automobile air conditioning system typically takes about 30 minutes. The process involves connecting an automotive vacuum pump to the low-pressure port of the AC system and turning it on for approximately 15 minutes in order to draw out all moisture, air, and contaminants from the system. After that, leave the pump running for another 15 minutes or so while monitoring its pressure gauge until it reaches a negative reading of at least -29 inches of mercury (inHg).

At this point, shut off the pump and disconnect it before adding refrigerant oil and recharging with R134a refrigerant per manufacturer specifications.

It is important to take your time when pulling a vacuum on the car’s AC system. Depending on the size of your vehicle and how long it has been since the system was serviced, this process can take anywhere from 15 minutes to an hour or more. Be sure to use a reliable gauge set and good quality vacuum pump in order to ensure that you are able pull a proper vacuum and diagnose any issues with the system before refilling it with refrigerant.

How to Pull a Vacuum on an AC System – Step by Step

How Long Should You Vacuum down Ac System?

When vacuuming down an AC system, it is important to make sure that you take the necessary time and care. The length of time required for this task will vary depending on the size and type of system, but generally speaking a full evacuation should take anywhere from 30 to 60 minutes. During this process it is important to check for any air or moisture leaks in order to ensure that your AC system can run efficiently and effectively.

Additionally, if your AC system has been idle for some time you may need to conduct a deeper vacuum in order to remove all pollutants from the lines before running them again. All-in-all proper vacuuming down of an AC unit can help keep it running smoothly while ensuring optimal cooling performance with minimal energy consumption!

How Long Does It Take to Pull Vacuum on Car Ac?

It typically takes about 30 minutes to pull a vacuum on a car AC system. This may vary depending on the size and age of the system, but generally you will be looking at around half an hour or so. During this process, all air is removed from the AC lines in order to eliminate any moisture that has built up over time.

After the vacuum has been pulled, it’s important to wait another 20-30 minutes before adding refrigerant and beginning the recharging process.

How Long Does Pulling Vacuum Take?

The amount of time it takes to pull a vacuum will vary depending on the type and size of the system being evacuated. For smaller, single-stage systems, typically containing one or two components, it can take approximately 30 minutes to achieve full evacuation. However, larger multi-stage systems containing many components may require several hours in order to properly evacuate all the air.

Additionally, if you’re using an older system with leaking valves or hoses, then this could add time onto your overall evacuation duration as well.

Do You Pull a Vacuum on the High Or Low Side?

When it comes to pulling a vacuum, the answer is both. Both high and low sides need to be pulled in order to properly evacuate an air conditioning system. On the low side, this process should begin with closing all of the valves on the suction line and connecting a manifold gauge set and hose assembly to each service port.

After that, you will then open one of the valves slightly so that you can create suction from your vacuum pump. On the high side, you’ll want to start by opening up all of the valves in order for air pressure to escape as quickly as possible while still allowing liquid refrigerant into your AC system’s components. Once this is done, connect your manifold gauge sets and hoses into each respective service port before beginning evacuation.

With both sides now evacuated properly, you are ready for recharging!

How Long to Pull Vacuum on Car Ac System


How to Pull Vacuum on Car Ac

Pulling a vacuum on a car’s AC system is an important part of the maintenance process for any vehicle. It helps to ensure that the air conditioning system works as efficiently and effectively as possible by removing all moisture and contaminants from the system, allowing it to perform better and last longer. To pull a vacuum on your car’s AC system, you’ll need to first connect your vacuum pump to both sides of the AC manifold using special hoses.

Once connected, turn on the pump and allow it to run until the gauge reads 0 psi or -29Hg (depending on what type of gauge you’re using). After this has been achieved, turn off your pump and disconnect it from your vehicle. That’s all there is too it!

Do You Vacuum High And Low Side Ac

Vacuuming high and low side AC units is a necessary step in the maintenance of your air conditioning system, as it helps to prevent dust and debris from accumulating on the condenser coils. This can help maintain optimal airflow within your home, as well as reduce energy costs by ensuring that the unit runs efficiently. Additionally, vacuuming these areas will help extend the life of your AC system and keep it running at peak performance for years to come.

Can You Pull a Vacuum on a Charged Ac System

Yes, you can pull a vacuum on a charged AC system. By pulling a vacuum, you are removing any moisture and air from the refrigerant lines. This helps ensure that your system is leak-free and running efficiently.

It also helps to protect your compressor from damage caused by excess moisture in the system. Pulling a vacuum should be done before charging your AC unit with refrigerant or after servicing it for repairs to make sure it’s sealed up properly.


In conclusion, pulling a vacuum on an automobile air conditioning system is a vital step in the repair process. It should be done slowly and carefully, as it can take anywhere from one to two hours or more to pull a full vacuum. The use of high quality tools and materials will ensure that your AC system is repaired properly and functions well for years to come.


Leave a Comment