How To Evacuate Car Ac System At Home?

how to evacuate car ac system at home

Are you wondering if it’s possible to evacuate your car’s AC system yourself at home without taking it to the shop? Many DIYers are intimidated by the thought of discharging and recharging their car air conditioning (AC) system, but with the right vacuum pump and tools, you can easily do it in your own garage.

Evacuating, also known as discharging the AC system, removes any remaining refrigerant, moisture and air from your car’s AC components like the lines, evaporator and compressor. It’s a necessary maintenance step before recharging your AC system with new refrigerant.

Read on to learn why evacuating is needed, when to do it, and step-by-step instructions for evacuating your car’s AC system at home using a vacuum pump.

Why Evacuating the AC System is Necessary

There are a few reasons why you need to evacuate your car’s air conditioning system:

  • Removes moisture – Water and humidity trapped in the AC system can lead to corrosion of components like the aluminum evaporator. It also reduces cooling efficiency.
  • Eliminates non-condensable gases – Air and other gases don’t condense into a liquid like refrigerant and lower AC performance. Evacuating removes any trapped air.
  • Avoids contamination – Old refrigerant and oil residues need to be flushed from the AC system before recharging to prevent contamination.
  • Detects leaks – The evacuation process will reveal any leaks in the AC system so you can repair them before adding new refrigerant.
  • Prevents compressor damage – Non-condensable gases can damage the compressor when it cycles on due to high pressure differentials.

Basically, thoroughly evacuating your car’s AC system ensures you are working with a clean slate before recharging and maximizes the life and performance of your air conditioning.

When to Evacuate the Car’s AC System?

when to evacuate the car's ac system

You should evacuate and recharge your car’s air conditioning system in the following situations:

  • After any major AC service where the system was opened up, such as replacing the evaporator or condenser
  • The AC is blowing warm air and not cooling properly even after recharging
  • There are signs of moisture accumulation like fogging from the vents
  • You experience icy cold air at times indicating a refrigerant leak
  • The compressor is making noises indicating mechanical issues
  • As preventive yearly maintenance to prolong the life of your AC system

Anytime the AC system is opened up for repairs, it allows air and moisture inside. The only way to thoroughly remove them is through evacuation. So if your car’s AC performance is lacking, evacuating the system should be your first step.

Step-by-Step Guide to Evacuate AC System at Home

step-by-step guide to evacuate ac system at home

Evacuating your car’s air conditioning system involves hooking up specialized tools to remove refrigerant, moisture and air. Here is a step-by-step guide to evacuate an AC system at home without taking your car to the professional shop:

Equipment Needed

Evacuating and recharging an AC system requires some specific tools and equipment:

  • Vacuum pump – This is connected to the AC system to pull out all refrigerant, air and moisture. Needed minimum CFM rating of 5 CFM.
  • AC manifold gauge set – Used to monitor system pressures and vacuum level. Should have low side and high side gauges.
  • Refrigerant recovery tank – Catches the remaining refrigerant removed from the AC system so it can be recycled.
  • Refrigerant service hoses – Hoses to connect the vacuum pump and manifold gauge to the AC service ports. Use R134a compatible hoses.
  • Wrenches – To open the low and high side AC service ports before connecting hoses
  • R134a refrigerant – The type of refrigerant needed to recharge most modern car AC systems
  • AC oil – For lubricating the compressor and seals after evacuating the old oil

Optional items include a refrigerant scale to measure the correct amount of refrigerant, and a vacuum rated micron gauge to monitor the deep vacuum level.

Accessing the Service Ports

The first step is to locate the low side and high side service ports on your car’s AC system. They will be located under the hood, typically on the passenger side:

  • The low side port is connected to the evaporator outlet and accumulator
  • The high side port is connected to the condenser outlet

Use the wrenches to remove any covers on the service ports. Then connect the manifold gauge’s hoses to the service ports – blue to low side, red to high side.

Connecting the Vacuum Pump

Your vacuum pump will also have a charging hose you connect to the center port on the manifold gauge set. This gives the pump access to the AC system through the gauge.

Make sure all the manifold valves are closed initially. Also connect a spare hose from the pump inlet to a refrigerant recovery tank. This separates and stores any refrigerant removed.

Starting the Evacuation

Once everything is setup, turn on the vacuum pump. Monitor the low side pressure gauge as it pulls a vacuum. The vacuum level will steadily drop over 10-30 minutes.

Let the pump run for at least 45 minutes. It needs to achieve an “deep vacuum” under 500 microns to ensure all moisture and air is removed.

Checking for Leaks

After initial evacuation, close the manifold gauge valves and turn off the vacuum pump. Wait at least 15 minutes then check the system pressure.

If the pressure rises rapidly, you likely have a leak. Check all connections and evacuate the system again to fix any leaks.

Final Evacuation

Once leak free, run the vacuum pump again for another 30 minutes under 500 microns. This ensures the system is ready for recharge with no traces of air or moisture.

Monitor your micron gauge reading if you have one installed. The vacuum level will hold steady when complete.

Shutting Down the Equipment

With a full vacuum achieved, close the manifold gauge valves and switch off the vacuum pump. Disconnect all the hoses and lines from the AC service ports.

You are now ready to recharge the system with new refrigerant! Make sure to first add the specified amount of compressor oil before recharging with refrigerant.

Tips for Proper AC System Evacuation

tips for proper ac system evacuation

Follow these tips to safely and thoroughly evacuate your car’s air conditioning system at home:

  • Only use premium vacuum rated hoses to handle the low pressures. Standard hoses can collapse
  • Inspect o-rings before connecting manifold gauge set. Replace if cracked or damaged
  • Change vacuum pump oil frequently to maintain maximum pump performance
  • Keep all gauges, lines and ports clean to prevent introducing debris into system
  • Monitor vacuum level with a micron gauge for most accurate readings
  • Achieve vacuum below 500 microns for minimum 45 minutes to remove all moisture
  • Conduct a leak check before disconnecting tools to prevent pulling air back into system
  • Research the specific refrigerant type and oil specifications for your vehicle
  • Add UV dye to the system to help you spot future AC leaks

Evacuating removes all traces of old refrigerant, moisture and gases from your AC system for a clean slate. While it takes longer than a simple recharge, evacuating is the only way to thoroughly prepare your AC system for new refrigerant and ensure optimum cooling performance.

Evacuating Your Car’s AC System Without a Recovery Machine

Many DIYers wonder if a full refrigerant recovery machine is necessary for evacuating their car’s AC system.

The good news is you can evacuate and recharge your AC system without an expensive professional recovery unit. All you need is a basic vacuum pump and manifold gauge set.

A recovery machine is designed to capture the old refrigerant instead of just venting it. But refrigerant released from a single DIY car AC recharge is negligible and not worth the cost of a recovery machine.

Your vacuum pump removes refrigerant along with moisture and air from the AC system during evacuation. Simply attach a recovery tank to the pump inlet to store the small amount of refrigerant safely.

Recovery machines are more critical for shops working on multiple cars everyday. But for occasional DIY AC repairs, a vacuum pump and manifold gauges are sufficient.

Follow the steps above to safely evacuate your car’s AC system without taking your car in to the shop and paying for an expensive recovery machine service.

Finding an AC Shop to Evacuate the System

If you don’t want to invest in the tools and equipment to evacuate your AC system at home, you can also take your car to professional auto repair shop instead.

However, just adding refrigerant without an evacuation is not an effective long term solution. Any decent AC shop should insist on evacuating the AC system first before recharging.

Here are some tips for finding a qualified AC service shop to evacuate and recharge your car’s air conditioning:

  • Search for shops certified to work on R134a systems – They will have the approved equipment to properly handle refrigerant.
  • Check for ASE certified AC technicians – This validates expertise in AC diagnosis, repair and evacuation.
  • Inquire about their evacuation process – A thorough evacuation typically takes 45-60 minutes with a high CFM vacuum pump.
  • Ask if they will demonstrate leaks if found – This verifies leaks were detected and addressed.
  • Get an itemized cost estimate – Evacuation, refrigerant, oil and leak detection should be clearly listed.
  • Compare pricing among highly reviewed shops – Prices can range from $100 – $300+ depending on location and car model.

A qualified AC shop should be able to effectively isolate and remove moisture while checking your entire system for leaks. This gives you the best shot at permanent AC repair versus quick refrigerant top-offs.

Is Evacuating the AC System Difficult?

While evacuating an AC system requires specialized tools and know-how, it’s not an extremely difficult job. The process itself is straightforward:

  • Safely remove refrigerant and store it
  • Connect pump and pull initial vacuum
  • Run pump for minimum 45 minutes to achieve deep vacuum below 500 microns
  • Check for leaks throughout the evacuation
  • Disconnect after verifying full vacuum and no leaks

The most technically challenging aspects are:

  • Using the manifold gauges – Understanding how to connect, open valves and monitor pressure/vacuum readings.
  • Finding AC service ports – Locating the specific low side and high side ports on your car’s AC components.
  • Detecting very small leaks – Finding leaks that cause pressure to rise slowly can require diligence.
  • Achieving deepest vacuum level – Pulling a “deep vacuum” below 500 microns requires a pump with sufficient CFM rating.

With proper instructions and some mechanical aptitude, evacuating a car AC system is certainly doable. Patience and attention to detail will lead to a successful evacuation.

Carefully follow the step-by-step process outlined above. Seeking advice from experienced DIYers or AC technicians is also recommended to help avoid mistakes on your first evacuation.

Conclusion – Thorough Evacuation is Crucial for AC Repair

When your car’s air conditioning is underperforming due to leaks, moisture or wear, a quick refrigerant recharge is not enough. To fully restore cooling performance and durability, the AC system must be evacuated.

Evacuating removes all contaminants and creates a “blank slate” for your AC to operate like new again. While adding refrigerant may provide temporary cooling, it cannot root out accumulated moisture or small leaks.

With some DIY knowledge and the specialty vacuum pump equipment, you can evacuate your car’s AC system yourself without paying a shop. Just be sure to check for leaks and achieve a deep vacuum before recharging for best results.

Overall, understanding how to properly evacuate a car’s air conditioning system will allow you to diagnosis underlying issues and conduct repairs that last. Say goodbye to lackluster AC cooling and hello to cold air once again with a thorough evacuation and recharge!

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