Hi! My problem its quite Unique… When im Stopped or in slow traffic, drive and stop, and the AC is on, the car dies, then starts again but it is very weak and the engine light comes on… Im from small town and already pass in all mechanics… no solution so Far, Sorry for my english
Check the battery and alternator with a voltmeter; it sounds like it might not be able to handle the AC being on.
Also check how much current the AC is drawing. Mine was overfilled with oil and was pulling way too much current and causing the same issues. Also: mass air flow sensor, oxygen sensors etc
I’m not sure about the Fiesta, but on other Ford models I’ve had, a faulty power steering pressure switch caused idle issues whenever the AC was on.
Take your car to the mechanic mate!
When was the last time you serviced your car?
Talk to your mechanic
He might help
Check the battery of your car
Sounds like not a big issue
Is this a Ford Fiesta really?