have 2007 T&C Touring. While driving or at idle, lights dim when fan turns on. When using heated seats the lights pulse.

That car comes with a standard 80 amp alternator, just because of all the bells and whistles that it has, using a lot of the features at the same time, that 80 should not have a difficult time keeping up, it should put out enough so the lights won't dim as you describe. Lights "pulse"? like dim then get bright again repeatedly? I would have the alternator checked to see if it is performing properly

some have said that it could be a ground issue. Is this possible?

Yes, it's possible. Very much so.

Your battery is old. Your alternator is old. Your belt is old. The belt tensioner is old. The electrical system is having trouble keeping up with the increased electrical load. You have lights, fans and seat heaters all drawing power that isn't called for in the summer months. You also have the battery recharging right after the engine is started. The easiest fix is to replace the belt, battery and maybe the tensioner. Slip it into neutral when waiting at a stop light so the engine revs higher and the alternator spins faster.

Hey man, I'm old. My seat is giving me trouble, and my tension is high though. I can't rev up until noon. I think I need replacement. ****all in fun tenspeed****