Passenger side mirror

I have a '97 Silhouette that the mirror and motor assembly broke off the mirror housing. I've been trying to find the housing and assembly to replace it. My original came with a four wire harness and all that I've found via internet and retailers are 3 wire. I never knew that my side mirrors were heated but I guess they are. My question is.....would it be recommended that I splice the 3 wires and isolate the fourth? It's my wifes van and I worry about her driving without this mirror. I live in Southern California so I would't think that a heated mirror would really be needed. Thanks in advance for any/all replies.