Temp gauge comes on with AC on sitting at lights or traffic.off when speed resum

What is your question?

Sitting at lights or slow traffic it comes on. I turn off AC and once moving get speed up and light goes off. Today I noticed wiggling in the upper engine and a flutter sound like a loose belt or???

What makes this problem better or worse?

Motor idling with A/C on in traffic.

How long has your 2011 Ford Fiesta had this problem?

Approximately 1 week