Overheating

What is your question?

We recently replaced a broken cooling fan in my Lexus, the plastic blades were broken off of the electric motor. The other fan was still in working order. I left my car running for about 15 minutes without the AC on and when I came back it was overheating again and the fans had not kicked on. So I shut he engine off to allow it to cool off but when I started the engine back up the fans came on. Could this be a relay problem or something more serious?