Ford Repair: 96 Taurus cooling fans, fans run, twin fan

Question
my 96 Taurus cooling fan/fans do not come on when engine gets hot. turn on a/c and both fans run and cool things down. swapped fan relays, now both fans come on when engine gets hot. Also both still come on when a/c turned on. relays are identicle. should I leave as is or replace relays? Thanks for any sugg.

Answer
replace the relays.  It probably doesnt matter if they both come on at the same time, as long as the engine gets cooled down.  The problem is only that the second is a good backup and should be replaced.  Both relays need to be working good.  I dont know how the twin fan setup works as far as when they switch on but im guessing ones a backup fan for when its realy hot.