on my 86 firebird..all sensors were replaced and wiring is good and fan comes on when ac is turned on..now, the question: can a piece in the computer be bad, affecting the fan not coming on by itself? 2) could fan relay switch be bad, even though it was bought new? 3) anything else i could be over looking at this point? thanks..its a single cooling fan

 

well if all sensors and relays were replaced then you might try lookign at your wiring now.