Fix AC - Car Air Conditioning Blowing Hot - Freon Refill

You turn on the air conditioning in your car and it either blows out semi cool air or hot air.  The most common cause is that some or all of the freon has leaked out.  You need to refill it.  

Here's a quick explanation (and video below) on how to refill the AC for your car with Freon refrigerant.
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AC Not Cold - Fix Car Air Conditioning Blowing Hot 


Since you are reading this, it probably means that you have never done it before.  That means that you not only have to buy the freon can, but also need the pressure gauge and hose.  When it comes to the cost or prices, there is a wide range.  DO NOT go to a place like AutoZone or Advanced Auto, etc.  The cans there cost upwards of $40.  Although i'm not a fan of Walmart, they have freon at half the auto store prices.  
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Connector hose and gauge.
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Since you need the hose and gauge, you probably want to buy them together.  The cost for the big can is around $20 to $30 dollars.  When you are done, throw out the can but keep the hose and gauge.  If you have to refill the car next year, just buy the can and reuse the gauge.

If your car is blowing out HOT air, you probably need the big can.  If the air coming out is semi-cool, you can buy the smaller can.
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Screw on the can to the gauge and open up the hood of the car.  With the car off, connect the snap fitting to the LOW PRESSURE air conditioning aluminum pipe.  Find your compressor and follow the LARGER aluminum pipe back until you find the fitting with the screw cap.  This is the low pressure line.  The smaller line is the high pressure, you don't need this.

Low pressure line - Connect to this
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Smaller high pressure line - Don't use
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Low pressure line after removing cap
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Pull the snap fitting back on the hose and press down onto the nipple fitting until the snap seals shut.  It takes a bit of force, but you will know when it's locked.
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Now start the car and turn the AC on and fan to HIGH.  
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Go back out and check the gauge.  It will probably read low or zero.  There should be a "zone" of where the pressure in the line should be.  The optimal pressure is between the red lines between 45 and 55psi.
psi range for car AC air conditioning, gauge

Invert the can so that the hose is pointing down and pull the trigger, putting freon into the system.  Hold the trigger and shake the can for 30 seconds.  
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Then check the gauge.  The small can will become empty after 3-4 minutes of this.  
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Hopefully you are within the acceptable zone before the can is empty.

And that's it.

Remove the snap fitting, unscrew the can and throw it out.  Hopefully the air coming out of your vents will be ice cold.  It should be an immediate improvement.  If it still isn't blowing super cold, then you may need to use a second can. 

If your car goes back to blowing hot air in a few hours or a couple of days, it's because you have a leak.  You will have to go back and buy a special freon detector kit, around $30.  
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This is suppose to seal any small leaks in your system.
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This kit comes with glasses, a black light and special freon that glows when a black light is shined on it.  
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You fill up the system, then several hours later when it's dark, use the black light to find where the leak is.  The freon will have leaked out and the dye will glow when the light is shined on it.  You can then try to fix the leak.

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