Cadillac Repair: 1993 Caddy Sev, ground wires, simple test

Question
installed new engine...both fans not working...engine over heats...how do I know if one or more of the relays are bad?  what do you think could be causing this problem?

Answer
Are you POSITIVE that you attached the GROUND wires for the fans ?.

I can provide an electrical schematic and simple test procedures to test the fan relays.

Is or HAS the CHECK engine light ever illuminated on the dash ?.

If so, What codes are oyou getting by simultaneously pressing the OFF and WARMER button for 3 seconds and releasing them ?