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How do i check the refrigerant level of my car AC?

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To perfectly check your AC level you need to understand the components that makes up the unit such as compressor, condenser, evaporator. But the simplest method is to check if the air coming out from dash vent inside the car is cold, Another method is compressor clutch engagement method, if the compressor clutch does not engage it mean there is low refrigerant but also note it another issue could be responsible for this. The other method is to use of gauge to check the air pressure from compressor but this needs a more expertise experience. 
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The proper method is to use a set of refrigeration gauges and a vapor temperature chart. But in case you don't have the gauges. Symptom of low refrigerant is diminished cooling, rapid cycling of the compressor clutch, or the compressor not coming on at all.
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An important note to consider is if your car takes R-134A refrigerant. The easiest way to tell is by the year your car was manufactured. Before 1994, cars used R12 refrigerant which you currently need a special license to purchase and use. If your car was manufactured in 1994 until the current day, it will use R-134A freon which can be purchased and used by anyone.

Another thing to note is that there are many other reasons for your AC not working. Little or no freon present happens to be the most common issue, so in this guide we will be covering the most common fix for recharging your AC. If you follow these steps and your AC still isn’t working, more than likely there is another problem that needs to be fixed, and the issue goes further than simply needing more freon.

With that said, here is your step-by-step guide to checking your freon level and recharging your AC by adding more freon.

Step 1 – Open the hood of your car and locate the low-pressure service port.

The AC compressor can only compress gas and cannot compress liquids, so it is critical that only freon gas enters the AC compressor. Some liquid freon may flow out of the accumulator through the evaporator coil into the accumulator where liquid refrigerant and oil is stored.

The low-pressure service port is located between the compressor and the evaporator. An easy way to find it is to locate the larger of the two AC lines. The low-pressure service port on the larger line also has a smaller valve than the high-pressure port which is found on the smaller of the two lines. Many times, the cap on the valve of the low-pressure service port will have an “L” on it.

If you’re using the combo R-134A with recharger hose and gauge kit from the list of tools provided above, the quick-connect coupler will only attach to the low-pressure service port. This makes it easy to avoid making mistakes when recharging your AC.

Step 2 – Turn on your car and the AC.

Turn the key and start the engine. Turn your fans to the maximum air setting. Turn on your AC. If you have a “Max-AC” feature, turn this on as well. If you have a “recirculation” feature, turn this on as well.

Step 3 – Run a low-pressure service port AC diagnostic.

With the car still running, attach the coupler from your recharge kit to the low-pressure service port. Simply remove the cap from the port and push the coupler onto the port. Make sure the can of freon is disconnected when testing your freon level.

While pressure is engaged, at this point you will take your reading. Use the gauge that is attached to the hose to find out how much freon is in your AC unit.

If the gauge shows refrigerant levels in the red zone, it means you have too much freon in your system, and this requires an entirely different service that may require a licensed technician. If your pre-diagnosis was correct, you should expect the gauge to show your system having low or no freon.

Step 4 – Set up for the addition of freon.

Disconnect the coupler from the low-pressure service port. Shake the can of R-134A freon for a few seconds and connect it to the gauge. Then reattach the coupler to the port the same way you did before.

Step 5 – Add the freon to your system to recharge your AC.

Start by holding the can upright. NEVER point the can upside down as this could cause liquid freon to enter your system. You want to add freon in a gas state.

While holding the can upright, squeeze and hold the trigger to release freon and begin shaking the can up and down while upright. You want to give it a few shakes up and down, then rotate your wrist 90 degrees shaking the can from an upright position to a sideways position a few times. Alternate between an upright up and down shake and a wrist rotation shake, never pointing the can downwards.

Step 6 – Check the freon level on the gauge.

After about 10 seconds, release the trigger and hold the can in an upright position to check the gauge. The needle should be moving from the LOW zone into the green zone. If the needle still isn’t quite in the green, squeeze the trigger again and repeat the shaking process from step 5. Don’t repeat the process for so long that the freon level gets into the red zone. Too much freon is just as bad as too little freon, and it can be a more difficult process for removing freon from the system. Too much freon can also damage your AC compressor.

*Important Advice* – Sometimes it will take a few minutes for freon to get through your entire system to provide an accurate gauge reading. It is recommended that if the needle has moved closer to the green zone to drive your car for a few minutes and then take another reading, as this will be more accurate.

Step 7 – Enjoy your recharged AC system.

As soon as you’ve added enough freon into your AC system, your car should be producing colder air almost immediately. As stated above, it could take a couple minutes of driving to get the freon all the way through your system. Take a short drive and note the difference in temperature of your AC. If your AC clutch wasn’t triggering before, you should have definitely heard it click on during your recharge process, and your AC will now be recharged.
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The best way to check the refrigerant level of your car is to use a car refrigerant meter. This tool gives you a reading every time you turn your car on and off, so you can track the level over time.
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To check the refrigerant level of your car AC, you need a refrigerant pressure gauge. Attach the gauge to the low-pressure port on the AC system, start the engine, and turn on the AC. The gauge should read within the recommended range for your vehicle. If the reading is too high or too low, have a qualified mechanic address the issue.
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First, turn on the car. Then, in the dashboard, click on the system it is already running in. In the system thunderbar, click on the refrigerant level button.
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turn on your vehicle air conditioner and listen closely,if you hear a click  with significant to clutch engaging . If the Freon level is too low the clutch will fail to engage
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Open the hood.

Attach refrigerant gauges to the low- and high-pressure ports

Turn on the car

Next, turn on the A/C to cold with the recirculating setting on

Place the thermometer into the center vent

Let the vehicle run for a few minutes

Check the gauges
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Place the thermometer in the center vent of your vehicle and allow the car to run for a few minutes. Read the gauges once the pressures stabilize. The low port should read between 25psi and 45psi, and the high port should read between 250psi and 400psi. If both are low, you are likely low on refrigerant.
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