GoodRevs

I noticed today that for about 2-3 seconds after I shut off the heat there is a whirling sound - like a fan slowing down - coming from the passenger floor vent. I never compared before, but the air flow seems to be stronger from the drivers side (no whirling sound) than the passenger side. I am wondering if there is a separate blower motor for each side, and if the passenger side is dieing? This is on a 2001 ES.