A recent Blue Print ProTip explained how the cabin filter for the traction battery compartment, can cause problems with the hybrid traction battery cooling fan. The subject of the ProTip were Toyota Prius ZVW30 & ZVW35 models, but this problem problem could occur on other makes and models for similar reasons.

Problem
The hybrid traction battery cooling fan is inoperative or provides poor cooling output. The high-voltage battery pack is overheating. Fault codes P0A82 or P0A84 are logged in the battery cooling fan control module.
 
Cause
The most common cause of this problem is the cooling fan becoming blocked by a build-up of dirt and dust from the interior air intake located to the right of the back seat. The Prius models mentioned above do not have an intake air filter for the high-voltage battery cooling fan fitted as standard. Instead, the fan itself becomes the filter. The fan is located upstream of the battery and collects particulates over time.

Solution
Inspect the battery cooling fan for excess debris. Take off the luggage compartment flooring and right-side trim panel to gain access to the fan module, then remove it from the vehicle and inspect. Using a vacuum cleaner and compressed air, clear away any dust, lint or debris build-up from the hybrid battery cooling fan blades, control module and air ducts of the hybrid battery cooling system. Reinstall the hybrid battery cooling fan assembly and verify its normal operation. Repeat this procedure every 15,000 km if the vehicle is used by a lot of back-seat passengers (taxi) or is used regularly to transport pets such as cats and dogs.

It is recommended to install Blue Print filter ADBP250046, which clips over the interior air intake to reduce the build-up of dirt and dust from the interior to the cooling fan. Therefore, reducing the risk of the battery overheating and premature failure.