That is a very good question. You need to look in your off door side front storage compartment behind the panel that covers the area by the universal docking center. On the new units coming offline currently, the hose actually comes out of the UDC, but on the earlier units, it is behind the carpeted divider. If you remove the screws and look back behind that area, you will see a hose that you can put in your bucket of anti freeze and use the pump to circulate the anti freeze throughout the unit. If you have any further questions, please don't hesitate to give customer service a call at 877-262-8032. Take care, Mike