• Always check to make sure the unit's display is not showing the empty tank symbol. If shown drain the unit;
• Check the setting and make sure the room temperature is warmer then what the unit is set at;
• check that the exhaust hose is connected to the unit properly and make sure there are no kinks or bends in the hose;
• check that the filter is clean and free of dust and debris.

Note: if this does not resolve your issue you may contact us at this link  or look for the closest service center here