How to Recharge an Air Conditioner

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Recharging an air conditioner can really be a very simple job. Many times, weekend mechanics shy away from dealing with the air conditioning system because they do not fully understand how it works or why refrigerants inside the system are treated as controlled or hazardous substances. Today we’re going to a look at how to recharge your air conditioning system after we discover how to find out whether or not your system needs recharging or has another problem that requires a different solution.

Does my air conditioner need to be recharged?

Since new air conditioning systems do not have any way for visually inspecting the system to determine if you have the proper amount of refrigerant, you likely have discovered something is wrong with your A/C because it isn’t as cold as you would like it, or isn’t cold at all. Since there is no dip stick or sight glass to look at, the best way to determine if your air conditioning system is working properly is by testing the pressures in the system. Your air conditioning system has a high pressure side and a low pressure side. As you would expect, the low pressure side is before the compressor where the refrigerant is warm and low pressure, and the high pressure side is after the compressor has increased the pressure of the refrigerant. To get a full picture of the performance of your air conditioning system, you need to check both the high pressure and low pressure side of the system to ensure the proper pressure increases and decreases. You also need to know approximately what the pressures should be for your system. The working pressure depends on the refrigerant used, not the particular system. If your car used R-134a, the most common automotive refrigerant, your low pressure side will be around 40-50 psi and the high pressure side will be over 250 psi.

Since the high pressure side works at such a high pressure, it’s rarely important for the weekend mechanic to measure the pressure there. You can pick up a low pressure gauge at your local auto parts store to measure the low pressure side of your air conditioning system. Take it home and attach it to the low pressure port of your air conditioning system. This will be on the air conditioning line coming from the fire wall and going down to the compressor attached to the front of your motor. Pressure must be checked with the car running, the air conditioning on and with the compressor cycling. You can make sure the compressor is cycling by making sure the center of the pulley on the compressor is spinning with the belt. If you watch it for a few minutes you will see the center of the compressor pulley intermittently engage and disengage as the system maintains normal system pressures. If you have low pressure, say 20 to 25 psi your system is low on refrigerant so you must add more for colder air.

How do I recharge an air conditioner?

Now that you have proven you need to add refrigerant, or recharge your air conditioning system, we’re on to the simple task of adding more. You should always be careful when handling R-134a refrigerant, as it has been known to be harmful to the environment. Now, depending on how low the pressure is in your system, you may require a large amount of refrigerant to be added. Some air conditioning systems require up to 4 lbs. of refrigerant, so if a considerable amount has leaked out, you may need to add quite a bit. You also should consider sealing your system to protect any further refrigerant loses. The connections in your air conditioning system are sealed by O-rings that can leak small amounts, and some of the hoses transition from metal hard lines to soft hoses and can develop slow leaks as well. To protect against future refrigerant leakage, add BlueDevil Red Angel A/C Stop Leak to your system along with any lost refrigerant. BlueDevil Red Angel comes either in a convenient aerosol can with an easy to use quick coupler connection, or in a bottle to be used with an oil injector. Simply connect the coupler of the aerosol can to the low pressure port of your A/C system, dispense the can, and all of your leaks will be sealed!