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AC - How to refill the AC in your car

2025-10-21

Important information before you start

Before refilling your AC system, make sure it is completely tight. If you detect leaks, broken components must be replaced. Always wear safety glasses and gloves when working with the AC system.

Leak detection: Fill the system with a small amount of gas and use soapy water, an electronic leak detector or UV lamp to identify any leaks. Our AC refill page contains everything you need for leak detection and refilling. Frostycool 12a contains a citrus/lime fragrance to help detect small leaks and a DYE tracer for effective leak detection with UV light.

Safety: Frostycool is flammable, just like hairspray, gasoline and lubricants. Avoid smoking and other sources of ignition while working. Make sure you work in a well-ventilated area. Enligt lag så behöver man vara certifierad fackman för att fylla på ac själv.

Step-by-step: How to top up your AC system

1. Check the charge quantity. Look for an information sign in the engine compartment or check the vehicle manual to find out the recommended charge quantity. Frostycool is more efficient than traditional refrigerants and only needs to be filled to about 35-40% of R134a or R12.

2. Locate and prepare connection

Find the car's low pressure port, usually located on the thicker pipe between the compressor and the torpedo wall.

  • Unscrew the protective cap on the valve.
  • Take out your filling hose with quick coupling.
  • Turn the tap counterclockwise so that the can needle does not puncture the can.
  • Connect the can to the hose, but leave the tap untouched in this position.
  • Connect the quick coupling to the car's low-pressure port (it only fits here, so there is no confusion).

3. Start the car and prepare the AC system

  • Turn on the car.
  • Set the AC control to maximum and the fan to the highest level.
  • Check the pressure on the pressure gauge to see if the system needs filling.

4. Refill with refrigerant

  • Turn the tap clockwise until the can is punctured.
  • Then turn the tap back to open the flow.
  • You should now feel the refrigerant flowing into the system and the pressure on the gauge increasing.
  • Continue filling until the compressor starts and the can is completely empty.
  • When the system is full, close the tap at the can.

Pressure measurement:

  • The system is fully charged when the pressure gauge reads between 25-45 psi.
  • At an outdoor temperature of 20°C, with the condenser fans operating and the motor at 1,500 rpm, the final pressure should be about 30 psi.
  • Warning. If the pressure exceeds 60 psi, the compressor may be damaged.

5. Check the cooling effect

  • Measure the temperature of the car's air outlet - it should now be blowing cold air.
  • Let the AC system run at maximum for about 5 minutes so that the coolant is evenly distributed.
  • Check the pressure gauge again.

6. Finish the refill

  • Turn off the vehicle.
  • Disconnect the quick coupling from the low pressure port.
  • Put the protective cover back on the valve.

7. Final check - leak check again. Do a final leak check to make sure the system is tight and working properly. Want a complete AC kit for easy refilling? See our range!

Extra steps when using FrostyCool A/C Stop Leak or System Sealer

If you use FrostyCool A/C Stop Leak or System Sealer, drive your car for at least 45 minutes after filling to allow the sealant to circulate, lubricate o-rings and seal any small leaks.

Now your car's A/C system is refilled and ready to provide coolness on the road! You can find our most popular ac refill kit here.

Author

Johan Karapetyan is product manager at SC Styling and has over 14 years of experience in product range, purchasing and technical advice. As a trained car mechanic with solid experience, he has helped thousands of customers find the right car styling and aftermarket parts.