Before use remove 2 pouches from side of 5 liter container and addcontent inside the reservoir supplied with Air-Conditioner System Cleaner Gun (part no. 4090). Now top up with 1 liter A/C System Cleaner.The activatedA/C System cleaning fluid is now readyto besprayed directly onto the surface of the evaporator with the flexible spray probe. Use 1 liter of cleaning fluid per application. Please observe the application instructions of the device or vehicle manufacturer. If there are no model-specific instructions from the manufacturer, you can find application instructions for different vehicle types at www.liqui-moly.us/service/ac-system-instructions. Apply only in well ventilated areas. For optimal results and a lasting effect it is recommended to redo the cleaning treatment at least every 12 months. Always replace cabin filter when servicing.