What I believe is a 'blower' above the master bedroom in my house is starting to make noise when we run the air conditioning. I've crawled up there and looked at the unit and it says 'Aire-Flo by Lennox'. The noise doesn't start immediately. We usually shut off the AC once the noise starts. Any ideas?

Bad motor or support bearing, broken motor mount allowing the fan to hit the enclosure. Possible A coil touching the plenum. Turn off the system and then switch the fan setting to "on ". Hear the noise? If so it is in the fan. If no noise, it is in the AC.

We did what you said. The noise only persisted when the AC was on. Didn't make noise when it was 'fan only'. So a guy came out and he's going to replace the motor. What a fair price to pay? He quoted me $731 which seems a little steep to me.

Well, that does sound a bit pricey, however, any component related to lennox seems to be extremely expensive, so as far as lennox goes, it may be a "fair" price. Maybe call in another non lennox company and see if you don't find a big difference in the installed price. You may be able to have a universal motor installed that meets all of the requirements of the original motor for much much less money.

That price appears to be very high. If you didn't hear the noise in "fan only ", was the motor running? If the fan was running and you didn't hear the noise, the motor is OK. The air handler motor has nothing to to with the AC, per se, it circulates heated and cooled air.