rear right passenger vent

Should be sucking air in, for the hybrid battery.

 

Hearing that fan running is usually not a good thing. It almost certainly means your battery is overheating and possibly on the verge of failure. Have you ever cleaned the fan? There are videos on YouTube showing you how to do it. Hopefully, the fan just needs to be cleaned and doing that will cause it to run at a lower speed. If that doesn't help, you'd better start planning to refurbish or replace the hybrid battery.

 

Definitely dont assume his battery is failing just because he can hear the fan. Thats just going to freak himout for no reason.

I do agree its good to check the fan if its never been cleaned, It might be going bad or maybe you just never noticed the sound before and its still working just fine. It only takes 15-30min and its very simple with all the videos online to follow.

 

I don’t think the battery cooling system is connected to the taillights

 

No, but the side panel you have to remove to do the tail light change, ALSO exposes access to the hybrid battery vent fan.


-Graeme-
2004 Prius with >190,000 miles.
Sent ?.

 

A little of this and a little of that, and Prius overreact

 

That is definitely some crud, alright. Was the car driven with the panels taken out for some period of time allowing that stuff to collect? There would normally be nothing there if it had been covered by panels and carpet the whole time. The fan can survive a little bit of dust, although if it is covered with it, its efficiency will be reduced. Some of that stuff looks like gravel. If that got into your fan that would be a little more serious. You didn't say that you heard anything rattling when your fan was running, but it's definitely worth checking if you are going back in to make sure the ducts are lined up properly. (Removing the side panel should not have changed the alignment of the ducts, so it's hard to see how your working on the taillight would have affected that).

If turning off the car and letting it rest for awhile before you drive it again reduces the fan noise, I think that is another indication the battery is heating up as it charges, which is not a good sign. I've been advised not to "freak you out" about the battery, but I do think it would be worthwhile to get hold of an OBDII scanner (available online for $10 - $15, make sure to get one with the ELM 327 chip) and the Dr. Prius or Hybrid Assistant or Torque app on your phone to see if there is anything going on with your battery that might be a concern.

 

So sick of irrational ill-informed fear making from people who don't know how a Prius normally operates. If you don't know how to repair hybrid batteries or don't know how the system regulates it's temperature, please don't post "advice" about how you think its failing... It's not helpful to anyone.

 

I guess I should have left out the "possibly on the verge of failure" part. Apologies to the OP for unnecessarily alarming him.

I did hear the fan on running on our Gen 2 once after we had climbed Mount Charleston near Las Vegas. I shut down the car and half an hour later when I put it back in 'Ready' mode I heard the fan roaring. Checking the Torque app I saw all 3 of the temperature sensors reading near 50 degrees C. I believe the middle one showed 56.4. I really did think the battery was toast. That was 2 and half years ago and although I know the battery is weakening, it still has not thrown a code. I guess it's important to know what conditions resulted in the fan running at full blast. I've driven the car enough to know it is not normal. In my case, I believe heat soak accounted for our issue, lacking a better explanation.

 

I assume you bought this used? Because that isn't a 2011; the Gen 3 Prius does not duct the battery fan to the pressure relief vent at the back of the car.

That said, if you can hear the battery fan occasionally then you know it's still working. I hear mine quite often in the summer.

 

Why did this get moved to the 3rd gen section? the pictures clearly show a 2nd gen prius.

 

?? your bad, what????