why does the blend door motor keep cycling from hot to cold on 1998 GMC Jimmy

I replaced the blend door motor on my 98 jimmy and when I plug it it and watching it before I put it in place ,it cycles back and forth nonstop while the key is on, what is the problem/

Get Your Car Fixed at a RepairPal Certified Shop.
We certify shops based on expertise, quality work, and verified customer reviews
0 answers