A/C Pro

The ABC’s of Automotive A/C Recharge

Your air conditioning system can be pretty complex if you don’t have a basic understanding of how your A/C works. At A/C Pro® we help folks bring back the cold with our line of quick and easy to use all in one auto A/C recharge products. We encourage drivers to get to know their cars, how they work, and how they can make repairs themselves. But don’t be afraid to pop the hood! We’re here to give you a better understanding of how the different parts of the system work together to bring you that ice cold air.

The ABC's of Automotive Recharge
(Photo Source)

Ambient Temperature

Ambient temperature is the temperature of the air around your vehicle your A/C system needs to cool make you comfortable.

Blower Motor

The blower motor forces air through your car’s vents. You are able to control the speed of the motor through switches, buttons, and dials on the dashboard. The motor and fan assembly is mounted near the evaporator and draws air from either outside or inside the car over the evaporator.


The compressor is the heart of the A/C system and is a pump that increases refrigerant pressure and temperature. Low pressure, refrigerant gas from the evaporator enters the compressor and is compressed into a hot, high pressure gas as it travels to the condenser. Compressors cannot compress refrigerant in a liquid state. For a deeper dive into this key component, check out our #PopTheHood series on compressors.


This is a hygroscopic agent that can dry or remove moisture through absorption. A desiccant bag can be found in the receiver-drier in vehicles with a Thermal Expansion Valve (TXV) system or in the accumulator for orifice tube systems.


The evaporator removes heat and moisture from the air coming from the passenger compartment. In this component, cooler liquid refrigerant changes to a gas as it absorbs heat from the air.

Freezing Up

An air conditioning system can freeze up and ice. The culprit? There’s two common problems–either the unit is low on refrigerant, or there is an airflow problem. Things like a dirty air filter or blocked evaporator coil can cause the restriction.


A gauge is gauge is a critical tool for recharging your vehicle’s system. When professional technicians check a vehicle’s A/C system they also use a set of gauges to check pressure.  The A/C Pro® gauge reads the pressure in your A/C system and provides instant and accurate feedback on your system’s refrigerant level with its premium coupler that easily connects to your low-side pressure port with just a simple push.

High Pressure Service Port

The high pressure lines route high pressure refrigerant gas and liquid through the compressor, condenser, receiver-drier, and expansion valve. It’s along these lines you’ll find the high-side service port used to service the high pressure side of the system. We do not recharge on the high side. So how can you tell the difference between the high and low pressure ports? There are a few visual cues; first, the high pressure line is usually smaller in diameter than the low side line and the pressure port valve is shorter in comparison to the low pressure port. To make it 100% foolproof, our hoses are designed to only connect to the low side port.


Isn’t it illegal to handle refrigerant yourself? Not at all! While section 609 of the EPA’s Clean Air Act states that technicians must be certified to repair or service, this does not apply to consumers simply adding refrigerant to their vehicles. A/C Pro® is safe and easy to use.  It’s true that some older refrigerants have been removed from the market, and can only be bought or used if you have the proper permits and licenses. But the R-134a used in cars today (and in cans of A/C Pro®) is considered safe and simple enough for anyone to use, and can be bought off the shelf at most any auto parts store or in the auto department of major retailers.

J2776 Standard

The SAE Standard J2776 sets a maximum level of 40 ppm for unsaturated impurities in R-134a. What does this mean to you? Double bonds in unsaturated molecules are more chemically reactive than single bonds, which increases the likelihood that a refrigerant will contain contaminants, contributing to the formation of system sludge. Impure refrigerants are harmful to a cooling system and can cause mechanical problems resulting in a loss of cooling, and the need for expensive repairs. A/C Pro® has high purity standards to eliminate the problems impurities can cause. Our refrigerant meets SAE Standard J2776.


The pascal (Pa) or kilopascal (kPa) as a unit of pressure measurement is widely used throughout the world in countries that use the Imperial measurement system and has largely replaced the pounds per square inch (psi) unit, except in the United States. 1 kilopascal is equivalent to 0.145037738 pounds per square inch.

Low-Pressure Service Port

The low-pressure port is where you connect to the A/C system to recharge it with A/C Pro® (or seal leaks with Super Seal). The exact location of the port varies between different car models, but can be easily found on any vehicle. It runs from the compressor back towards the passenger compartment and is the thicker of two metal lines coming out of the compressor. On that line you’ll find the one and only valve covered by a plastic cap, which you can unscrew to access the service port. You can be certain you’ve found the correct port by simply attaching the coupler on the end of the A/C Pro® hose to it. If it’s the low-pressure service port, the connector will easily snap on and lock into place.

Model Year/Make

One of the most frequently-asked questions we get at A/C Pro® is “How do I find the low-pressure port on my car?” That’s because the low-pressure service port is where you connect to the air conditioning system to recharge it with A/C Pro® (or seal leaks with Super Seal). The exact location of the low-pressure port varies between different car models.

New Refrigerant

There is a new refrigerant called R-1234yf (or HFO-1234yf) that is beginning to be used in some brand-new cars, mostly in Europe. It was developed to meet the European directive 2006/40/EC that went into effect in 2011 which requires that all new car platforms for sale in Europe use a refrigerant in its A/C system with a Global Warming Potential (GWP) below 150. R-1234yf has a GWP of 4, while R-134a has a GWP of 1430, making R-1234yf significantly better for the environment.

Orifice Tube

The orifice tube is a metering device that restricts the flow of refrigerant leaving the condenser. This changes the liquid refrigerant from high pressure to low pressure. A metal mesh screen catches debris that may be traveling through the system. Because the orifice tube does not meter refrigerant by temperature it becomes possible for liquid to pass through the evaporator and onto the compressor. An accumulator always accompanies an orifice tube design to prevent any liquid refrigerant from ever entering the compressor. Compressors only compress gas. Compressing liquid will damage the compressor.


PSI or “pounds per square inch” relates to pressure when it comes to recharging. Those are the numbers you see along the outside of our gauge face. When adding refrigerant, it’s important to get the A/C system pressure within the correct range. Having too much pressure is just as bad (or even worse) as having too little refrigerant. But the correct pressure range changes with the temperature; that’s why A/C Pro® gauges have a rotating dial that you can set to the current outdoor temperature. The gauge will then show the correct pressure range for that temperature. As long as you stay within that range and don’t overfill, you should end up with comfortably cold air!

Quick and Easy

What makes A/C Pro® so simple to use? It’s been specifically designed to be as close to “foolproof” as possible. Everything you need to recharge your car comes in a single can of A/C Pro® – no additional tools required. It can be used by people who know basically nothing about how a car air conditioner works or what refrigerant is. It requires no tools and no mechanical experience, making it literally one of the simplest car repairs you can do. A single can recharges the system with R-134a, seals leaks, eliminates corrosive moisture, and replaces lost lubricant—all in about 10 minutes, with no special tools required.


The “R” stands for “refrigerant,” while the numbers and letters identify which refrigerant you’re talking about. A refrigerant is a liquid or a gas with a very low boiling point. Where water normally boils at 212 degrees Fahrenheit (and freezes at 32 degrees), a refrigerant like R-134a boils at 15 degrees below zero (and freezes at -154). Since 1994, almost all cars use R-134a, including many old R-12 systems that have been retrofitted. If your car has not been converted, you can pick up a retrofit kit and do the job yourself!

Schrader Valve

Schrader valves of varying diameters are used on many refrigeration and air conditioning systems to allow servicing, including recharging with refrigerant. The spring-loaded valve itself is recessed inside a metal stem found inside both the high and low side charging ports. When recharging with A/C Pro®, our quick-connect couple depresses the metal stem allowing refrigerant to flow from the can into your vehicle.

Thermostatic Expansion Valve

In a TXV system (Thermostatic Expansion Valve), like the orifice tube (OT) system, meters and controls the flow of refrigerant. This restriction reduces refrigerant pressure and cools it as it enters the evaporator. However, unlike the OT, it controls the flow of refrigerant by sensing evaporator outlet-tube temperature and pressure to regulate the flow of refrigerant into the evaporator.


When an air conditioner is low on refrigerant, it loses its ability to cool the air in the car. A proper charge is critical to optimizing your A/C’s performance. An undercharged A/C system is also a major cause of A/C compressor failure. Low refrigerant means poor lubrication as lubricant flows through the system with refrigerant. So not only will you be sweaty, but you’ll be causing damage to a pretty expensive component. A/C Pro® can fix your undercharge problem, save you time, money and the unfortunate side effects of Sweaty Back Syndrome.

Vacuum Pump

Your system only needs to be vacuumed if you have replaced a component part in the system in order to remove excess air and moisture that has been introduced while opening up the system. There’s no need to vacuum out the system if the issue is just a small leak/lack of refrigerant as it is a closed system operation. A/C Pro® has additives that condition the rubber components (that are typically responsible for leaks) and eliminate moisture in the system.


Need a little extra help? Don’t worry, we’ve got you covered. Our customer support team is there to help. Our toll-free line is open 7 days a week during the summer season to answer your recharge questions. Simply reach out to 1-888-318-5454 between 8 AM to 7 PM (CST) Monday to Friday and we’re also available 10 AM to 3 PM (CST) on the weekends. Not up to talking? Fill out our Ask the Pro form and a customer support member will reach out to you at a time and method you prefer.


The old adage of “more is better” does not necessarily apply to charging your vehicle’s A/C system.  Adding excessive amounts of refrigerant beyond your system’s capacity will not give you colder air and can be damaging to the systems performance in the long.


Some people are visual learners. What better way to learn the ins and outs of your A/C than video? It’s the next best thing to being under the hood. That’s why we have a YouTube channel solely dedicated to showing you how to find your low pressure port, how to recharge your vehicle, money-saving repairs you can DIY, and how an A/C system works. Besides having great content, we also answer your A/C questions!

Zero Pressure

We often get asked why the pressure “drops” when adding refrigerant: “I pulled the trigger and my A/C dropped to 0 PSI and when I let go it’s 30 PSI, is that normal?” The reality is when you’re pulling the trigger; the gauge is not reading your system’s pressure. To get the actual pressure reading, you need to release the trigger every few seconds and be sure the compressor is cycled on to get the low side pressure reading on your vehicle.

Questions? Feel free to ask the pro. For more car tips and tricks, follow us on FacebookTwitter or YouTube.