Passenger Side Intake Fan

[mcomet]

Ok so I finally figured out what the new high whine I hear is... somewhat minor/quiet sound...comes and goes... Lately been cold and has started up when I start the car. It is coming from the fan on the intake on the passenger side of the car.

When I had things apart the other day I quickly checked and it seems to spin ok by hand. So either i am wrong and it is slightly hitting something, or there is a bearing within the fan on the engine making a subtle noise, or this is just normal.

Can anyone confirm if there is a sound with this? Also does anyone know what the passenger fan is for? I've done some searching and read everything from letting cold air IN, letting more cold air OUT, and something with catalytic convertors warming up when cold... heh.

thanks
comet

[thom4782]

Does the "fan" turn off between 1 and 1 1/2 minutes after starting. If so, it is the secondary air pump making the noise. This is perfectly normal when starting the car when its cold out. The pump puts extra air into the system to warm up the catalytic converters more quickly

[mcomet]

Yep that is what it does....makes sense as this started when it has gotten colder here. Thanks!