How to stop an auto AC refrigerant leak

Written by richard ristow
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Fixing a refrigerant leak can either be relatively easily or extremely complicated. It depends on the severity of the leak the car's air conditioner is experiencing. For the home mechanic, a severely damaged or leaking air conditioner should be left to a professional mechanic. Some of the tools and materials required will be expensive and hard to locate. However, a home mechanic should have no problem fixing minor refrigerant leaks. Cans of air conditioner stop leak products are widely available at most automotive parts stores.

Skill level:

Things you need

  • Air Conditioner Stop Leak.

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  1. 1

    Insert your key into the vehicle's ignition and start the engine. Let the engine idle until it reaches its standard running temperature.

  2. 2

    Switch the air conditioner on. Set the air temperature to the coldest level, and set the air conditioner's blower to the highest and hottest setting.

  3. 3

    Release your vehicle's hood and find the air conditioner's metal pipes. There will be two sets of pipes in the centre of the engine compartment. Find the wide diameter pipe that's connected to the vehicle's compressor. There, you will find your vehicle's low-side pressurised connector.

  4. 4

    Remove the blue or black cap from the low-side pressurised connector.

  5. 5

    Fill the stop leak canister's injector tube with about 59.1ml of stop leak fluid. Connect the injector tube to the low side service part and add the stop leak fluid.

  6. 6

    Remove the injector tube from the low-side connector.

  7. 7

    Connect a Freon recharging kit to the low-side connector. The kit's coupler will snap onto the low-side connector. Turn the nozzle atop the kit downwards and allow 60 seconds of Freon to flow into the air conditioner.

  8. 8

    Close off the flow of Freon and check the Freon recharging kit's pressure gauge. Wait 60 seconds before adding more Freon. This will allow the system to circulate the newly added stop leak fluid, as well as the newly added Freon.

  9. 9

    Detach the recharging kit's coupler from the low side pressure connector, once the kit's pressure gauge shows that the system has been charged. Let the air conditioner run another 15 minutes before turning the vehicle's air conditioner and engine off. This will allow the air conditioner's blower to fully circulate the stop leak fluid throughout the system.

Tips and warnings

  • If adding stop leak fluid does not solve the refrigerant leak, drive the vehicle to an air conditioning certified mechanic.
  • Be careful when adding Freon to your air conditioner. Do not attempt to recharge a R-134a Freon air conditioner with R-12 Freon. R-12 is used in pre-1984 vehicles, and adding it to a R-134a system will damage the air conditioner.

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