Hi all. I've got a heck of a head scratcher and was hoping I could bend the forums ear for a moment. My neighbor, a lovely retired senior citizen had me take a look at her outside unit because it was making noise. I've had a hand in a few repairs so I have some knowledge. She had her condenser fan motor and capacitor replaced about 3 months ago. Tech said to also replace the fan blade, but didn't have one. I contacted the manufacturer and got one for her a few days later and installed it. Her old one would make a growl/vibration sound for about 1/2 a second at start up and then noise would be gone. Tech said the fan was out of balance, hence the replacement. After replacing with one I got from Goodman, #B1086775S-(22", 27 deg pitch), it sounded fine at start up, no noise. Couple of days later it started developing a noise while running, that lasted a couple days and then went away.Funny thing with that noise was when it was running you could give it a little bump with your fist on the top panel above the motor mounting area and the noise would go away, but only for a few seconds. Anyhow, weeks go by and the original growl/vibration sound came back. Well last night it was making a heck of a racket, I could hear it in my house, noise lasted about 1 minute and then a final "crash" sound. I went next door and pulled the circuit breaker, took a peek inside the housing, fan is missing a blade. Further looking and it's lying in the bottom of the unit. It's a miracle in my opinion it did not puncture the coil. She had her old fan blade so I pulled the broken fan, fired up the motor for a couple of seconds to eliminate it as the problem, then installed the old, original fan. Turned it on, same noise as when it was originally on, that growl/vibration sound. Again, only lasts about 1/2 a second and only at start up. I got to thinking maybe they put in a 1075 RPM motor when the original was an 825 RPM. The motor is an Emerson K55HXCLF-586--1075 RPM, speeds 2, volts 208-230. I did some looking online for what her original motor would be and I found it to be also a 1075 RPM but 1 speed. Her unit is a Goodman CLJ48-1C. I'm afraid that this fan is going to to do the same thing. Anybody have this type of experience? I'm wondering if I need to look at the height of the blade in relation to the motor when installed on the motor shaft. I'm concerned I'm having a venturi problem with the fan deck. I've tried finding the spec's, but I can't find it. Tech that replaced the motor had installed the fan on the shaft with the hub about 1" from the motor. I replaced the fans in the same location. I wonder if the techs location was wrong and that's what's causing all the noise. I've attached some pics of the broken fan. Thanks for any help.