How To Recharge a Window Air Conditioner – Easy Guide

| Last Updated: August 17, 2021

When the air temperature in your home starts to feel like the air outside, it may be because your air conditioning unit needs recharging.

It may be because the coolant has run low or the unit has a leak, which leads to inefficient cooling.

We’ll guide you through the process, and you can decide if you’re up to it or prefer to pay an expert to do the job.

Photo credit: popularmechanics.com

Quick Questions Before Starting

All AC units require regular maintenance at least every two to three months. If your unit’s cooling efficiency dwindles, it’s probably because the coolant has expired. The coolant, Freon, is a colorless CFC gas that’s responsible for cooling the air. If the coolant leaks, the unit won’t work efficiently.

How Difficult is This to Do?

We’d suggest letting the experts handle this, mainly because Freon is toxic.

How Long Does it Take?

It should take about 45 minutes to recharge your unit if you follow the instructions carefully and correctly.

How Much Do Materials Cost?

There are different recharging kits available, ranging from a basic DIY kit for $40 or less, a moderately priced kit with a range of cleaning components for $40-90, and the more expensive kits for $90 or more, which include a high-powered vacuum and various other components.

Materials Needed to Recharge a Window Air Conditioner

If your unit uses Freon as a refrigerant, you’ll be able to purchase a Freon kit from a hardware store or even online. The kit comes with instructions, which should be adhered to accurately. Freon is toxic and is to be handled with extreme caution. Materials needed for recharging your AC unit are as follows:

  • High-quality vacuum pump – $92-109

  • Pressure gauge set – $75

  • Three four-foot long hoses – $40

  • Valves – $18

  • Quick coupler – $40

  • Can tap – $10.99
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How to Recharge a Window Air Conditioner: Step-by-Step

If you want to save money, it’s possible to recharge your unit yourself by carefully following the instructions provided. It may be worth it to pay an expert if you’re not comfortable with your understanding of air conditioners. You should also make sure that you understand the laws of your state. These are the steps to recharging your air conditioning unit once you have purchased your Freon kit:

Make Sure That the Unit Isn’t Plugged in

Make sure that the unit is unplugged and not in direct contact with the floor. It’s extremely dangerous to open the unit when it’s still linked to a power source.

Also, take further precautions in wearing safety goggles and suitable gloves when handling Freon.

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How to Open the Unit

Find the correct size screwdriver if one isn’t provided with your kit and open the unit. There should be an instruction booklet that came with the unit, which will guide you to the correct way of opening the unit.

It’s a good idea to clean the blower wheel, air filter, condenser coil, and evaporator coil before beginning the recharging process.

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Do a Safety Check

Ensure that the unit inside is intact and that there’s no damage to internal parts or leakage. If there’s water pooling around the unit or ice and frost inside the unit, it means that there’s a leak. It’s best to ask the experts for help in these instances.

How to Put Freon in the Air Conditioning Unit

Ensure that the temperature inside the unit is cooler than outside. Freon naturally looks for the coldest nearby temperature and won’t react efficiently if the air outside is cooler.

The kit comes with two lines that are to be attached to the service and tap valves. These must then be attached to the Freon container. The unit’s manual should tell you how much Freon it requires, and there should be a detailed diagram showing where to locate the compressor inside the unit and position the coolant tank correctly. 

It’s vital to follow the instructions carefully, and it’s recommended that an expert carry out the process.

This diagram is an example of a Freon kit hooked up to an AC unit.

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Begin the Recharge Process

First, make sure that you have the correct Freon as indicated in the unit’s manual. Once everything is securely connected, open the Freon canister by turning the spout beneath the canister. 

Attach the yellow hose to the canister’s valve and the other end to the gauge’s middle valve connection. Twist the small nodule on the bottom of the canister to open it. Plug in the unit and turn it on to its highest setting. Leave it running for several minutes to stabilize itself.

Refilling will begin automatically. Continue to open and close the nodule every few seconds to allow small amounts of refrigerant to flow into the unit for a time until you reach the intended temperature.

The correct cooling temperature can be found on the rating plate. Use the gauge to monitor the temperature and be ready to switch the unit off again once it has completed filling.

Twist the nodule on the canister to stop the flow of refrigerant and disconnect all hoses and the gauge from the unit.

Very carefully remove the valves and store the kit in a safe place.

How to Tell if Your Window AC Needs a Recharge

If your AC unit is no longer functioning efficiently, it probably means that it needs a recharge. However, it’s easy to mistake other problems for the insufficient refrigerant. 

There are signs to look out for:

An Increase in Your Energy Bill

If your energy bill has increased in recent weeks with no significant changes in interior air temperatures, it could mean that your unit is leaking refrigerant. Without insufficient refrigerant, the unit is unable to exhaust as much hot air in the cooling cycle, and the unit will have to work harder to cool the surrounding air.

Warm Air Escaping From the AC Vents

You may find warm air escaping from the AC vents if the unit can’t exhaust it outside efficiently. 

Frost or Ice Forming on the AC Unit

This is a definite sign that refrigerant is low, causing the refrigerant’s temperature to drop below intended temperatures. This could cause frost and ice, as well as water pooling around the AC unit.

The AC Unit Is Making a Hissing Noise

A strange hissing noise could indicate the escape of refrigerant as gas leaking in a liquid form.

Photo credit: onehourairftworth.com

Tips and Safety Considerations When Recharging a Window AC

Here are some considerations when performing this process:

Fixing a Leak

If you suspect your unit leaks, we suggest investing in an electronic leak detector or pay a certified expert to test the unit for you. Freon is toxic and legally must be handled by a trained professional. Check your state laws to make sure of what’s allowed and what’s not legal.

It would be best if you evacuated the remaining refrigerant first before adding fixing the leak and adding more refrigerant. It’s necessary to add the correct amount of refrigerant as specified in the unit’s manual.

The Recharging Process

We recommend paying an expert to handle this process; however, if you’re confident that you’re well prepared and understand the process, follow the recommended guidelines carefully. Any errors could lead to damaging the unit and possibly the surrounding area.

Make sure that the unit isn’t connected to any electrical outlets.

Ensure that the system pressure is always lower than the pressure in the charging canister.

Be careful not to discharge refrigerant from the wrong side of the canister as the process will reverse and the canister will begin filling up. High pressure always flows to the low-pressure side.

Keep the canister in an upright position when charging.

Photo credit: hvachowto.com

Always wear protective gear and ensure that your hands, eyes, skin, and lungs are protected when working with refrigerant. It is worth purchasing a good quality pair of safety glasses and appropriate gloves. 

Never inhale refrigerant as this can lead to death and if you get refrigerant on your skin rinse immediately and seek medical attention. 

Old refrigerants and units should be disposed of in the correct manner. 

Follow the necessary guidelines and have a professional handle the removal and disposal of refrigerant and units as refrigerant is toxic to the environment and, if mishandled, could be released into the atmosphere.

Conclusion

In conclusion, it’s possible to recharge your unit yourself, but we highly recommend paying a qualified expert to do the job due to Freon’s toxic nature.

If you’re prepared to recharge the unit yourself, make sure that you follow all the necessary diagrams, hints, and tips that will be available in the unit’s manual and the Freon kit. 

Photo credit: rollingstone.com

People Also Ask

Here are some frequently asked questions that could assist you if you find that your AC unit isn’t functioning efficiently due to a leak.

Do You Need to Recharge Window Air Conditioners?

Yes, a window air conditioner also uses refrigerant in the cooling process, and the unit may no longer cool the air efficiently once the Freon runs low and it begins leaking.

Can You Recharge Your AC Yourself?

Some states specify that only a qualified HVAC professional may recharge an AC. You should make sure before attempting to handle the process yourself, and make sure that you follow the directions for handling refrigerants carefully.

How Much Does it Cost to Recharge a Window Air Conditioner?

The price of recharging kits ranges from $40 to $90 and over. The less expensive kits won’t last long and are ideal for easy DIY jobs. Moderately priced kits will last longer and are easy to use. The most expensive kits are more complicated to use and come with all the necessary equipment for recharging an AC.

Do You Have to Put Freon in a Window Unit?

You do need to replace your refrigerant when it runs low; however, a product called Puron has been developed as a more environmentally friendly product in place of Freon.

How Often Do You Need to Recharge AC?

You should never have to recharge an AC unless the unit has developed a leak.

What Kind of Freon Goes in a Window Air Conditioner?

Freon kit used to refill the AC unit. Before 2010, window units primarily used HCFC-22 Freon. It’s now being replaced with R410A, Puron, as it’s more environmentally friendly.



My name is Bob Wells and I am a retired HVAC tech from Washington state. I am currently retired and no longer do much with HVAC, however, I feel like I have a lot of knowledge in the subject and I wanted to create a website where I could talk about what I've learned and help upcoming HVAC techs. Find more info about me and HVAC Training 101.