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Sometimes you only need to make a quick fix to one part of a system, but if you’re starting a do-it-yourself air conditioning job, it’s a good idea to take a look at the whole system. That’s because replacing or fixing the compressor, valves, hoses, and the accumulator can extend the life of your AC System—and save you an additional trip under the hood.

Always remember to have your system flushed of refrigerant before working on it. If there is any refrigerant in the system, it must be legally recovered by a qualified AC technician. Find a repair shop.


Your air conditioning works best when it's free of contamination. When a failure occurs, the system needs to be cleaned with a thorough flush and replacement of parts that can hold onto contamination and debris.

This guide lays out the three tools that are crucial to a complete AC repair job.

3 AC Tools to do the Complete Job

1

Manifold Gauges Keep Tabs on Refrigerant Pressure

Manifold gauge sets are designed to measure pressure automotive air conditioning systems systems. They have three hoses: the blue hose connects to the low-pressure side of the system, the red hose connects to the high-pressure side, and the yellow hose connects to a refrigerant refill can.

The set can be used to refill a system that's gotten low on refrigerant, but these tools are more versatile than a simple recharge gauge like come attached on some cans of refrigerant, this gauge will only tell you the low-pressure. A manifold gauge set will measure both high- and low-side pressures, and you can compare these pressures to the pressures specified in the owner's manual or on our guide: How to Recharge AC. By measuring both sides of the system with precise gauges, the set can be used to test your system by reading the pressure of both sides of the system.

Too much pressure on the high-side indicates too much refrigerant in the system, a restriction or air in the lines, or insufficient airflow at the condenser. Too little pressure on the high-side is often caused by low refrigerant levels or a bad compressor. Excess pressure on the low-side indicates too much refrigerant or a defective compressor. Insufficient low-side pressure means there is a restriction on the low-side of the system, or insufficient refrigerant or airflow across the condenser.

They can also test to ensure the system can maintain a vacuum. If the system cannot and pressure is decreasing, your system has a leak. It will also tell you how much vacuum the system can maintain should you decide to use a vacuum pump.

2

Flush Kits Clean Out Your AC System

AC flush kits use a special flushing liquid and compressed air to flush the system clean of debris and other contamination. Some components may not need replacing but will need to be flushed out to keep from contaminating the new components. It flushes everything except for the accumulator and compressor which should be disconnected before flushing. This allows it to clean out your evaporator, condenser, and AC system lines.

The kits must be filled with both a flushing solvent and compressed air. The air forces the solvent through the system to ensure that the whole system gets properly cleared of debris.

3

Vacuum Pumps Remove Moisture and Check for Leaks

Using a vacuum pump is often overlooked when performing the complete job. Applying a vacuum for 45-60 minutes will accomplish two things: removing moisture and checking for leaks, setting up your repaired system for continued successful operation.

The ability of the system to reach and maintain a state of vacuum is a sign that the system should be leak free. If the system is unable to reach 29 in/Hg (inches of mercury, the unit of measurement used when measuring vacuum) of vacuum, or the vacuum fails as soon as the pump is turned off, a leak probably still exists in the system.

Get the AC Tools You Need Through the Loan-A-Tool® Program

These tools are available through Loan-A-Tool®. Just put down a deposit, borrow the tools you need, and get your full deposit back when you return them within 90 days. Check with a store associate at an AutoZone near you to find out if the specific tools you need are available.

Learn more about how car AC works and some of the most common AC problems.

Advice, how-to guides, and car care information featured on AutoZone.com and AutoZone Advice & How-To’s are presented as helpful resources for general maintenance and automotive repairs from a general perspective only and should be used at your own risk. Information is accurate and true to the best of AutoZone’s knowledge, however, there may be omissions, errors or mistakes.

Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

FREE Loan-A-Tool® program requires returnable deposit. Please note that the tool that you receive after placing an online order may be in a used but operable condition due to the nature of the Loan-A-Tool® program.

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