The battery pack fan in my 2015 Ford Fusion energi; plug in hybrid, runs almost constantly whenever the car is turned on. Usually the air temp is not hot and the fan comes on right away after starting car.
The dealer says this is normal and they can’t find anything wrong. The fan didn’t do this in the first 3 years we owned it.
You might try a different dealer. These are rare cars, so you might have trouble finding someone who knows their way around the battery system. Is there an air filter anywhere in the system? It could be plugged.
Idon’t know if this applies or not but this was an article in this month’s Rockauto newsletter. Filter, fan, relay.
Hair Decreases Fuel Efficiency
Speaking from the position of someone who is hair-challenged, I say bet on the baldest driver winning the race whenever you see a Toyota Prius and Ford C-Max facing off at the track. Hybrid vehicles like these typically have a Battery Cooling Fan system. Hair, lint, carpet fuzz, dust bunnies and other airborne debris can gradually clog the system reducing efficiency of the hybrid’s battery and eventually causing the battery cooling system to fail.
Fans on cars usually bring in outside air to cool extremely hot parts like the engine’s radiator. A fan also provides fresh air to a heat and air conditioning system that adjusts the interior air temperature to stay in a range that people prefer. It turns out that the big batteries in hybrid vehicles prefer the same air temperature range that people do.
A battery cooling fan pulls this not-too-hot, not-too-cold air from the hybrid vehicle’s interior, circulates it around the battery and then blows it outside and/or back into the interior. The battery cooling fan’s motor will wear out over time just like the blower motor in the heat/AC system.
Hybrid battery cooling fans face an additional challenge because they typically pull in unfiltered air from the car’s interior. If you ever changed a home furnace air filter, you know how surprisingly dirty interior air can be over a long time period.
As seen in the illustration below from the Chilton repair manual (found under “Literature” in the RockAuto.com catalog), the Prius’ battery cooling system pulls in air through an opening next to the right rear passenger’s shoulder. Think about all those Prius taxi fleets. That right-rear air intake is positioned to collect hair and lint from every taxi customer!
The good news is that worrisome battery efficiency or temperature related trouble codes on an aging hybrid vehicle might be fixed relatively easily with a new Battery Cooling Fan, a new Hybrid Battery Pack Cooling Fan Relay (often located near the fan) or maybe just by cleaning out accumulated debris. Find Battery Cooling Fans under “Electrical” and Hybrid Battery Pack Cooling Fan Relays under “Electrical-Switch & Relay” in the RockAuto.com catalog.
Tom Taylor,
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