Make sure the Heating buttons have been pressed (listen for the fan). Make sure the hose on the bottom of the bed is attached. To attach the hose, first press the TV preset to give clearance under the mattress to access the hose. Pull the hose connector down to the base and align the connector tabs with the fan outlet of the base. Insert and twist until locked into place. Ensure enough time has been given for the mattress to heat up (at least 30 minutes).
Please note that sheets/blankets on the mattress will facilitate warming by trapping heat. Ensure the filter on the fan is clean and unclogged. To clean the filter, press the TV preset to gain clearance to access the filter(s) in the base. Remove the filter by grasping the handle and pulling up. Clean the filter using a soft brush, compressed air, or with a vacuum attachment. Return the filter to the base and the base to a flat position.