The HV battery cooling fan in “severe usage” Toyota hybrid vehicles (2012-newer Camry HV, Prius C, Prius V, 2006-newer Highlander HV, 2010-2016 Prius and 2016-newer RAV4 HV) may exhibit an excessive buildup of dust, lint or other debris that can reduce the efficiency of the HV battery cooling system.
According to Toyota, this may be more predominant in vehicles that are used for over 15 hours per day, used over 6 days per week and/or where the rear seat is used excessively per day.
Refer to the appropriate service manual and remove the HV battery cooling fan assembly. Using vacuum and compressed air, clean any dust/debris buildup from the HV battery, cooling fan blades, control module, air ducts and internal/external filter of the HV battery cooling system.
Be sure to secure the fan blades to prevent them from turning while cleaning. Do not attempt to clean the HV battery cooling fan while it is installed in the vehicle. Doing so can cause dust/debris to enter the HV battery case.
Failure to secure the fan blades during cleaning can result in mechanical damage or electronic circuit failure due to excessive fan speed. Re-install the fan and verify normal operation.