My brother has a Trane XE900 condensor model# 724A100A0, his fan motor went out. So he purchased a new motor, but the old motor had 3 leads- 1 purple to cap. 1-brown to cap and 1-black to line voltage, and the new one has four leads 1-black to line 1-orange to cap. 1-orange to line 1-brown to cap, according to data label on motor housing. We wired it exactly like the old one was but don't know where the 1-orange to line goes connected. The strange thing is the fan comes on when the disconnect is set back on, with the other orange lead not connected. Can someone help me understand what im doing wrong

I'm trying to figure out what type of motor you got, seems like there would be two brown wires going to the cap. Just install both line voltage wires to the contactor and both cap wires to the cap.

Tell me what kind of motor you are working with.

It's a FASCO D832 1/8hp 230V 825rpm

That's an OEM Rheem replacement motor. From past experence if an OEM Trane motor is not avalible, I use a 1/4 hp with a close RPM range. I have had a lot of problems with 1/6 and 1/8 motors lately, OEM direct replacements sometimes still have issues. Check the amp rating on the motor and check the amp draw while it's running, make sure it's within range (example if it's rated @ 1.5 amps and your getting 2.5 amps it will be a short life).