How to Charge a Window Air Conditioner | A Step-by-Step Procedure

When the air temperature inside your house starts to feel like the air outside, it may be because your air conditioning unit needs recharging or troubleshooting

This can happen when the coolant has run low or the unit has a leak – leading to inefficient cooling.

Whatever the case, you will have to recharge the unit to restore its cooling capacity. While hiring a technician is an option, it will be cheaper to do it yourself if you know how to charge a window air conditioner.

What You Need to Charge Your Window Air Conditioner

Here is a quick look at what you will need. You’ll notice that some of the items in the list, such as the pressure gauge set, require some prior knowledge of how to use them to do the job successfully.

  • Pressure gauge set
  • Freon refill kit with at least two hoses 
  • Valves
  • A tap valve (bullet piercing valve)   
  • Protective hand gloves
  • Safety goggles
  • Screwdriver

Preparation Before Recharging Your Window Air Conditioner

In this section, we look at the critical steps to take before diving into the task of recharging your window AC.

These steps are for your safety and the safety of the environment around you. It is important to study them carefully to decide if you are up to the task or prefer to pay an expert to do the job for you.

1. Unplug the unit and remove the window out of contact with the floor

You will need to open the unit to recharge it. This can be very dangerous if the unit is still connected to a power source as it can lead to electric shock. So you want to ensure you power it off and remove it from the wall socket to guarantee safe handling.

2. Open the unit

Find the correct screwdriver to open your window AC unit if one is not provided with your kit. It can be a flat blade or Phillips head screwdriver.

There should be an instruction booklet that came with the unit to guide you in the correct way of opening it.

Once it is open, consider cleaning the window AC air filter, blower, condenser coil, and evaporator coil before recharging the unit with Freon.

Sometimes it is something other than the refrigerant causing your AC not to work correctly. Often, this can be any of the following:

  • Loose fan. If the fan is not spinning, the unit will not circulate cool air in your home. This problem will render it ineffective at keeping the temperatures down. You can fix this problem by tightening a small set screw on the collar of the fan.
  • Clogged condenser or evaporator fins. Accumulated dust or debris can block sections of your AC, making it unable to pass air through and cool your room.
  • Dirty air filter. Like most small air conditioning units, your window AC likely has a removable air filter near the front. Take it out and clean it as per your user manual to see if this fixes the issue.

You will need to try running the air conditioner for a few moments without the filter to see if it blows out sufficient cool air.

If none of these is the problem, it may be crucial to proceed with the recharge.

3. Carry out a thorough safety check

Ideally, you check to ensure that the inside of the window AC is intact, with no visible damage or leakage.

If there is ice or frost, or water pooling inside the unit, it would mean there is a leak.

If you are not sure about a leak but have your suspicions, you can invest in an electronic leak detector or pay a certified expert to test it out for you.

The refrigerant, also called Freon, will usually cause greenish-looking corrosion if there is a leak. You should never recharge the system before repairing a Freon leak.

Unfortunately, this repair is usually a complicated and expensive process, and your best option in such a case might be to buy a new unit.

However, it is best to consult a technician before deciding to replace your window AC. The leak might be too small to be problematic. Minor leaks like that can mean that a recharge will last several years to come, and replacement would be unnecessary.

Because of the sensitive nature of some AC materials, your state will have pieces of legislation around what is legal and what is prohibited. Be sure to check out these laws to avoid falling on the wrong side of the law. 

Unless you are an AC expert yourself, it is best to ask for professional help in these instances.

How to Charge a Window Air Conditioner Using Freon

By now, you should have determined the type of refrigerant in your window unit because the recharge Freon must be the same as the one currently in your system.

Most manufacturers used to go with R-22 in the past. The use of R22 has, however, declined in favor of R-410a refrigerant.

Units built anywhere from 2000 are likely to have the latter – which is now the most popular refrigerant. Recently, many manufacturers have started building air conditioners with R-32 refrigerants.

So, you will need to look at the label on your window AC to determine what type of refrigerant it contains before purchasing your refill kit (usually costing $20 to $30).

Your Freon refill kit should consist of a gauge with a hose already connected to each side of it. Ensure you get the correct type of gauge for the type of refrigerant you are putting into your air conditioner.

Step 1: Wear your protective eyewear and hand gloves.

Refrigerant can be harmful to your skin if it comes in contact. Therefore, you need to wear safety goggles and protective hand gloves when handling it.

Step 2: Look for the AC’s service valve.

The valve should look similar to a tire valve and have a cap on it.

Your unit’s manual should have a detailed diagram showing where to locate the compressor inside the unit.

From the diagram, you should locate the position of the service valve on the low-pressure line to the compressor. There will be two copper lines connected to the compressor; the larger of the two is the low-pressure side.

The manual will also tell you how much Freon the AC requires so you can stop the recharge once it reaches that limit. It will be vital to follow these instructions correctly.

Step 3: Attach a tap valve to the larger line

The larger of the two lines is the tube to which you will add the Freon. This is why you need to attach a tap valve to it by following the instructions that came with the valve.

Step 4: Connect the gauges.

First, check the gauges to ensure they are off, and then connect the blue hose to the valve you just attached. This blue hose should be attached to the blue side of the compound gauge.

Step 5: Charge the unit.

Plug in the air conditioning unit and power it on at its highest setting. Let it run for a few minutes, then connect the yellow tube to the refrigerant bottle.

Open the refrigerant valve and then loosen the yellow tubing at the gauge for about one second before tightening it right back. This is to release air from the tube.

Open the valves on each side of the gauge to start the flow of refrigerant into the unit.

Keep your eye on the gauges and let it charge the unit until it hits 70 psi (or the amount mentioned in your user manual).

Turn off the gauges and Freon, remove the tubes, and remember to close the new valve on the compressor tube where you inserted the recharge valve.

Step 6: Reinstall your AC

Power off the AC unit, unplug it and place it back in its housing. Once this is done, you can now reinstall the AC in the window. 

Final Thoughts

It is usually recommended that an expect carries out any Freon recharge exercise. Here’s a guide on hiring an HVAC technician.  

Nonetheless, if you plan to do it yourself, you can use this piece as a step-by-step guide to walk you through the entire process.

Hoping that now you know how to charge a window air conditioner. Let’s know your thoughts in the comments sections.

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Jesse Pinkman is a passionate HVAC professional writer who grew up repairing any home appliance on which he could lay his hands. He is responsible for ensuring that every article we publish is SPOT ON. When he's not in the office, he enjoys hiking, watching football, and spending time with his family.