90 3.9 EFI twin front fans different speeds

Been changing bulbs and realigning the headlights...
I noticed the twin fans on the front of the Rad were moving at different speeds...

Offside one spinnig happily, the Near Side one spinning like a cornwall windmill quite slow and easy to see each blade still while spinning.

Is this normal should they be in sync all the time ??? if so whats my best started for 10 ??

Thanks

Sounds like one fan is dead or just about to be. Change them out but keep your good one as a spare. The A/C fans on a classic are not controlled like more modern cars, they are either on or off - no speed control I am aware of.