How To Recharge Car AC


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So your air conditioning (AC) is blowing hotter air than a politician hoping for reelection Bummer! Rolling the windows down only goes so far, and sitting in a stagnant olfactory pool of under-thigh sweat and oil-rich exhaust fumes is a recipe for an uncomfortable and nauseating ride.

Contrary to the perceived belief that AC injects icy air into the cabin, an AC system creates the feeling of cool air by making the hot air less hot. It removes heat rather than adds cold. This is accomplished with a circulating system that includes both a compressor and a condenser and relies on refrigerant, which absorbs heat. The most frequent reason an AC system goes warm is a low level of that refrigerant. 

Luckily, that’s also the easiest thing to fix. To get you back to feeling icy and cool in the summer’s heat, The Drive’s informational team is here to show you exactly what you need, what to do, and how to do it. 

Now, let’s follow these steps to learn how to recharge car AC.

Recharging Car AC Basics

Estimated Time Needed: Half-hour

Skill Level: Beginner

Vehicle System: AC System

How Does Car AC Work?

There are seven main components of a car’s AC system. The system uses a closed-loop format and runs refrigerant throughout. Here’s the role of each piece of the puzzle: 

  • Compressor: Powered by a belt-drive, the compressor pulls in cool gas refrigerant, turns the refrigerant hot, and pumps the refrigerant through the AC system loop. From the compressor, the pressurized refrigerant goes through the high-pressure tubing into the condenser. 
  • Condenser: The condenser turns the gas refrigerant into a liquid refrigerant. The air passing through the condenser helps cool down the hot refrigerant and remove heat from the air conditioning. This cools the refrigerant into a liquid. From the condenser, the refrigerant moves to the receiver/dryer.
  • Receiver/dryer: A canister or reservoir that helps remove moisture from the AC system. If water gets into the system, it could freeze and damage an AC system’s components.
  • Thermal expansion valve/orifice tube: Between the dryer and evaporator is a valve that restricts the flow of the liquid refrigerant and lowers its temperature. This allows the refrigerant to expand and pressure to go down. 
  • Evaporator: The evaporator is typically located under the dash inside the car. Cool low-pressure refrigerant enters the evaporator and turns into a gas as it absorbs heat from within the cabin. 
  • Accumulator: An accumulator is typically located between the evaporator and the condenser. Similar to a receiver/dryer, it acts as a system filter and helps eliminate moisture, whether that be water or refrigerant.
  • Refrigerant: The refrigerant that goes in automotive AC systems is called R134a, or 1,1,1,2-tetrafluoroethane. It is a chemical gas that has a boiling point of 15 degrees Fahrenheit below zero. This boiling point rises, however, under pressure and condenses into a liquid.

Car AC Safety

Working on your car can be dangerous and messy, so here’s exactly what you’ll need to ensure you don’t die, get maimed, or lose a finger.

Additionally, working with cans of compressed air presents its own set of safety concerns. Never leave the pressurized can in direct heat or on top of a hot engine block. In extremely rare cases, the can could be heated to the point the compressed air explodes.

NOTE: Spraying refrigerant into the air is ILLEGAL.

Everything You’ll Need To Recharge Your AC

Take a quick trip to the local auto parts store, and you’ll be ready to go.

Parts List

  • Can of refrigerant
  • Hose connector, if not included with refrigerant.

Or if you don’t want to bother with a bunch of parts, and like to have everything that you need nicely organized in one place, then you can use an AC Recharge Kit .

Organizing your tools and gear so that everything that you need to recharge your AC is easily reachable, will save precious minutes waiting for your handy-dandy child or four-legged helper to bring you the sandpaper or blowtorch. (You won’t need a blowtorch for this job. Please don’t have your kid hand you a blowtorch—Ed.)

You’ll also need a flat workspace in order to recharge your AC properly, such as a garage floor, driveway, or street parking. Check your local laws to make sure you’re not violating any codes when using the street because we aren’t getting your ride out of the clink.

Here’s How To Recharge Car AC

Anybody who can follow instructions can recharge car AC. Get your glasses and gloves, grab the refrigerant and attachment hose, and let’s get chilly! 

  1. Turn the car on, make sure it’s in park, and put the parking brake on.
  2. Turn the AC to its coldest setting, crank the fan to its highest setting, and hit the button to recirculate the air.
  3. Pop the hood, find the AC low-pressure service port between the compressor and the evaporator, and remove the plastic cap. If you are unable to find the service port, A/C Pro offers a handy online port finder. A secondary method is to use the connector piece from the refrigerant hose, as it will only fit on the low-pressure port.
  4. With the attachment hose disconnected from the can of refrigerant, connect the hose to the low-pressure point.
  5. With the compressor cycling, look at the included gauge and rotate the temperature dial to the current temperature.
  6. If the pressure reading is in the red portion of the gauge, do not recharge. This is a sign of a bigger problem, possibly a faulty or malfunctioning compressor.
  7. If the PSI reads lower than the designated “full” area on the gauge, it needs more refrigerant. 
  8. Detach the hose from the service port. 
  9. Remove the safety tab from the can of refrigerant, shake the can, and reattach the gauge and hose to the can.
  10. Connect the hose to the low-pressure service port and use the trigger to begin recharging the system with refrigerant. Rotate the can up and down to maintain good refrigerant flow.
  11. Use the built-in gauge to determine when the system is full. Do not overcharge.
  12. Remove the connector from the port and recycle any empty cans according to local recycling laws.

You did it, congrats!

Get Help With Recharging Car AC From a Mechanic On JustAnswer

The Drive recognizes that while our How-To guides are detailed and easily followed, a rusty bolt, an engine component not in the correct position, or oil leaking everywhere can derail a project. That’s why we’ve partnered with JustAnswer, which connects you to certified mechanics around the globe, to get you through even the toughest jobs. 

So if you have a question or are stuck, click here and talk to a mechanic near you.

Pro Tips to Recharge Car AC

Over the years, The Drive’s editors have worked on dozens of vehicles and logged hundreds of hours wrenching under fluorescent garage lights. During our experiences, we’ve picked up a few tricks and noted the important things. Here’s what we learned in our times recharging car AC.

  • Do not overcharge the system with too much refrigerant. This could damage the system’s internal components.
  • If a system gets cold after recharging but reverts to pumping out warm air, there might be a leak in the system. An easy way to detect that is by using a refrigerant leak detector.

Related Post: Best RV Air Conditioners

How Often Do You Need To Recharge Car AC?

Refrigerant slowly leaks out of a car’s AC system, but there isn’t a schedule to follow for AC maintenance. If you own one of the AC pressure gauges, simply use that to check the system whenever the AC seems to be losing its cool.

How Much Does It Cost To Recharge Car AC?

A basic can of generic refrigerant costs less than $10. A can that includes a hose and a gauge will likely cost roughly $40-50.

Life Hacks To Recharge Car AC

Because you may not have access to the right tools, or have a friend you can bum a wrench off of, we also compiled our best hacks to make your life easier and drain your pocket less.

  • If you have access to a chain auto parts store such as O’Reilly’s, Autozone, or Advanced Auto Parts, you don’t need to buy the refrigerant with the build-in hose. These stores will lend you the tool to use with the can of refrigerant you just purchased.

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