I have a 04 Ls430 and my driver-side fan would spin (it is a bit loud tho) but my passenger side would not spin unless I spun it with something, or sometimes I would spin but very slowly. Does anyone have any ideas on what it could be? I can also hear the driver-side fan inside of the car as well.

 

That's wierd, because the same blower pushes air to both sides. You sure the vent is open?

If the fan is loud, the bearings might be clapped out. Not to worry: replacing the blower fan on an LS430 is easy as pie. I did it when mine got loud. The dealer wanted ~$950 to replace my noisy blower. Before agreeing to that, I checked out YouTube. There are plenty how-to vids there. The unit is right under/behind the glove box, and super easy to get to. An OEM replacement is kinda expensive in the USA; I ordered one from Japan and IIRC it was $360 shipped. That's not too bad, and swapping it into the car took less than five minutes all-in.

 

Not sure but think he is referring to radiator fans.

 

I was thinking radiator fans as well since there are two of them. They are run by the "Engine Cooling Fan Controller" which lives on the fan shroud with the fans. If the fans are spinning at seemingly incorrect speeds it could be the fan controller that has gone bad. Or, depending on your definition of spinning very slowly, the passenger side fan may have died and the fan controller is spinning the drivers side fan as fast as it can to try and make up for it. If it were me, I would test the passenger side fan to see if it can spin up to full speed by removing the fan shroud assembly and applying 12 volts directly to the fan motor. Or if I just had to take a guess I'd lean towards the fan motor since they have moving parts inside that wear out. I replaced that exact same motor on my friends car last year.

Here you can see an expanded diagram of all the fan parts. I don't know if those prices are current though, they seem slightly low compared to other dealers.
https://parts.lexusofpembrokepines.c...m--cooling-fan