102C3 Condenser fan motor runs backward

ChuckMC8 · April 06, 2010, 06:42:26 PM

I don't know how I accomplished this feat,maybe someone has a clue..I sure dont.
I changed the bottom bearing on our 102C3 Condenser motor yesterday (factory a/c system)-It was working but noisy...So, I pulled the fan motor assy and finally manage to get the fan off the motor

, I remove just the bottom cover and replace the bearing. So, I think all is well, put it back in the bus and the fan runs backward. (Pulls air off the ground and tries to force it out the condenser side door) It was blowing the opposite direction yesterday.
The fan only goes on one way and the 2 wires won't interchange due to the stud size. WTH could cause this?

wildbob24 · April 06, 2010, 06:57:09 PM

Chuck,

The only thing I can think of is the fan blade is on backwards. Is that possible?

Bob

philiptompkjns · April 06, 2010, 07:11:10 PM

Quote from: wildbob24 on April 06, 2010, 06:57:09 PM
Chuck,

The only thing I can think of is the fan blade is on backwards. Is that possible?

Bob

I don't think thats possible.

ChuckMC8 · April 06, 2010, 07:14:45 PM

Bob, I had to weld a couple of 3/8 nuts onto the fan hub to attach my puller, so I know that's the way it came off. I'm stumped

fe2_o3 · April 06, 2010, 08:38:22 PM

If the only thing you took off was the back. I would start there. Did you change the wire or brush location? Could something be rotated out of sequence? Were the brushes attached to the back? Could it be in a different position? Just some random thoughts...Cable

oldmansax · April 07, 2010, 05:06:07 AM

If it's a DC (direct currant) motor, reversing the leads (hot , ground) either internally or externally will result in the motor turning backwards. Most buses are DC.

TOM

niles500 · April 07, 2010, 11:19:37 AM

Don't know whether the fan motor was connected when you did the welding but Tom is right, reversing the leads "internally" may have occured during welding - FWIW

kyle4501 · April 07, 2010, 01:29:15 PM

Is this like 'flashing the field" to change polarity of a generator? Like what was done when a car was changed from positive to negative ground?

ChuckMC8 · April 07, 2010, 03:00:26 PM

OK, the problem is solved and the winner was.......Cable. Here's what happened. While I has the motor apart, although I didnt remove the top (with the brushes) I did 'spin' it to check the top bearing. When I put it back together I had the top/body relationship off 90 degrees. After reading Cables post, I realized that when it removed it from the bus, the motor ID tag was facing the rear and after I reassembled it, it was facing the condenser door.
This morning I removed the 4 quarter inch bolts that hold the motor together, rotated the top to the same configuration it was in b4, and viola, now it runs the correct direction.
I usuallymark anything that I take apart so that I can put it back the same, but didnt do it this time and it bit me on the butt.
Thanks for the replies and help.