Prius Has Two Cooling Fans -- But Only One May Need Cleaning

Dear Car Talk:

I have a 2017 Toyota Prius with 58,000 miles. Do I need to have the cooling fan motor cleaned periodically? I do not have pets or children, do not drive on dusty roads, or drive in areas with extreme temperatures. My dealer recommended this. -- Julia

Your car has two cooling fan motors, Julia. One of them is the traditional one, that helps push air through the radiator, to keep the internal combustion engine from overheating. That one does not need to be cleaned.

But you have a second fan that cools your hybrid battery. And you don't want that fan to get so dirty that your battery runs hot, because that will shorten its life. The hybrid battery is located under and behind the rear seat on your Prius. And if you look at the base of the rear seats (where your calves would be if you were sitting back there), you'll see a vent. Air gets sucked in through that vent, at different speeds -- depending on how warm the battery gets. If you used your Prius to carry hay bales on your ranch or if you had a golden retriever that rides back there, you can imagine that the fan can get dirty over time and lose efficiency.

But neither of those describes your situation, Julia. Fortunately, that vent also has a filter. So, if you want to give yourself some peace of mind, you can ask any mechanic to start by inspecting the filter for you.

That's a 5-minute job (as opposed to cleaning the fan, which can take a couple of hours). You just pop off the vent cover, pull out the filter, and have a look. If the filter is really filthy, or you find your lost Angora cat in there, that indicates that it's not a bad idea to have the fan itself cleaned.

If the filter isn't particularly dirty, you can just replace it (or even clean it with compressed air and put it back) and keep driving.

I'd say that unless your car is dusty, dirty, or you're missing a cat, you shouldn't need to clean the fan itself until you get to around 100,000 miles, if ever. Until then, check and clean the filter once in a while, and you should be fine.

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