Air Conditioning - Condenser vibration

Hello. I have an American Standard Allegiance condenser (about 5 years old) that seems to vibrating more than usual lately. It seems like the fan is running out of balance and when the unit turns off (and the fan stops), I can hear the fan blade just touch the side (the spine fin) as it slows down. When stopped, the fan blade is not visually centered either. Can the fan be adjusted? It seems like there are some screws under the center plastic cap, but I am not sure if these would allow me to re-center the fan blade. Is there a way to test if the fan is spinning true or causing vibration?

Thanks,
Richard

I hope it's not hitting the fins, the fan blade should in the plastic housing somewhat [the housing is called the volute]. It's possible the mounting is a lttle loose, the fan blade is out of balance, maybe the screw holes for the screws that hold the housing together are worn.

Thanks for the reply. I'm not sure I understand what you have written. Where is the volute? What I see looking down through the air discharge grill on top of the unit is a silver fan blade and motor that appears to be attached to the center of the grill. There is a plastic cover cap in the center of the grill (on the outside) that presumably covers the fan motor mounting screws. Can I remove this cover and adjust the position of the fan motor? How can I tell if the fan is out of balance?

The volute would be a conical shaped piece of plastic the the fan blade turns in. it's possible you don't have one. The mounnting screws under the cap should allow you to re-center the motor although those same screws may also be the motor mounting screws. Try slowly turning the fan blade by hand and see if something looks obviously bent.

Thanks for the help. I took off the plastic cap in the center of the grill, but I don't think the mounting screws under the cap allow for any adjustment. What is the best way to remove the fan and motor? Remove the screws on the cabinet (at the top of the sides) and pull off the top of the cabinet together with the motor/fan/grill? Is there likely to be some slack in the electrical connection to the motor or should I remove the electric cover plate or cabinet side and disconnect the motor wires first?

Are the mounting screws tight? Yes, disconnect the wires first but take some photos and make a wiring sketch. Then take off the top.

Yes, the screws under the plastic cap and on the cabinet (at the top of the sides) were tight. Is there likely to be bracket to which the motor is mounted so I can adjust the position of the motor on the bracket? I am hoping there is a bracket and one of the screws holding the motor is loose/missing, which would explain the vibration problem.

you should be able to see if there is a bracket, but I don't think there is one. Once you get it out, make sure the blade is tight on the motor shaft and try wiggling the motor shaft side to side. The shaft shouldn't have any play.

Thanks for the help. I finally got the time to take it apart. One side of the fan blade was bent down, so I bent it back to straighten it out and it's running ok. I guess I should replace the blade at some point. I also found a mouse nest under the electrical cover panel and the thermostat wires were almost completely chewed through, so it's good that I was able to catch that before it failed.

Btw, how do you remove the louvered panels for cleaning the coil? The first panel is easy because it's screwed on, but the next one (corner) seems really tight. Wasn't sure how to pull it out without breaking something.

Good catch. If they had eaten thru the wires, the short may have wiped out some controls. On Trane and AS units, it's much easier to pull the top and wash the coil from the nside out. Thanks for the feedback.