You have all the information you need. I suggest contacting a Trane or American Standard dealer about replacing the motor.

Thank you.

Am unable to get to the motor.

Most likely need to find contract to do this work. I am in Milpitas, near San Jose, CA.

I want to find out any alternative and better quality motor / blower out there so that I can replace better and quieter blower.

What size motor do you think I have? Any suggestion for better motor / blower?

Read more: http://www.doityourself.com/forum/air-conditioning-cooling-systems/500130-how-seek-help-replace-air-conditioning-indoor-blower-motor.html#ixzz2ZAM7qvun

How old is your furnace? How large is your house. I assume the winters in Milpitas are mild.

The motor is probably a 0.25 or 0.5 HP size. Your motor may have failed prematurely because either your furnace is too big for your house, and/or your duct work is too small. A furnace which short cycles puts a lot of wear and tear on the motor. In addition the motor has to do a lot of extra work if it is trying to push the air through a constricted filter or duct work. These things kill blowers.

I don't understand why the installer would limit the blower to run in the high stage only. This could also have contributed to an early failure.

Find an HVAC contractor who can evaluate your system. You don't have to find an industrial strength motor. The new motor will outlive your current furnace if it installed properly.

Thank you. The current motor doesn't seem failing. It just make louder annoying rattle noise. I think if I get this blower service, I may as well replace with quieter blower.

The house is around 2100 sq ft tri-level in south San Francisco bay in Silicon valley. The top floor is over 15F high than the bottom floor in the summer. That's why we limited the duct output on the bottom floor to get top floor cool.

Is there anyway to get replacement two speed motor which allow the motor speed manually set by external switch?

Thank you.

A rattling noise is not normal. It needs to be investigated.

The furnace and air conditioner have to run at the proper speed. If the fan speed is too slow, the furnace can overheat. This is a dangerous condition. It could also cause the coil to freeze when the AC is running. Running the fan too high is inefficient and will cause the motor to die early again.

Get a qualified HVAC tech to replace the motor set the appropriate speed. If your third floor is hot, then you either need to add more insulation or you need to improve the duct work up to the third floor. A 4 ton AC should be able to keep a 2100 sq. ft house at 75 degrees on the hottest summer day in the Bay area. You can't overcome duct work problems by playing with the blower speed.

Something else you might look at.... it might not be the blower motor at all. It could be the blower wheel starting to come apart. Most of the wheels have the veins pinched or squeezed on to the main hub. I have seen many loosen over time and even seen the hub spinning without moving the actual blower wheel itself.

You might also have a broken motor mount as well.

Hope this helps

replace the blower wheel+fan and AC motor 3/4 HP 1100rpm 4 spd, 110AC,
2 hours
total cost $460
the original was GE motor

Fair price in my opinion...