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This means that breathing low concentrations of freon from a leaking refrigerator or air conditioner over a long period of time is unlikely to have a cumulative effect, and thus few, if any, long term health effects.
This may happen if your unit is many years old, or there is some leakage in your house of the cold air. Contact a professional to fill up the right type of freon gas. There should be temperature difference of 20 degrees farenhite, if there is sufficient freon in the compressor.