BMW Repair: ac issues, bmw 323i, air temp

Question
Hi there, I have a 4dr 2000 bmw 323i. Recently -40 came on the dash and the ac stopped working, I did some research and found out about a sensor under the left front bumper that went missing. I beleive its called a temperature sensor. I replaced it with a new one and now the ac works in and out. Come to find out -40 is still on the dash. Is there another sensor that can affect how the ac now opperates. It works and then goes out for about 1 min. then comes back. Please Help thanks.

Answer
I don't believe that the sensor in the front has anything to do with the a/c.It is a temperature sensor but ambient temperature,(outside air temp.)When it reads a "-" its probably and open connection.The sensor that wasn't there why wasn't it? did it get pulled out and broken? check the wires