Someone could have wired a resistor in the wiring to 'fool' the fans into coming on. My PO had a relay rigged to run mine all the time instead of replacing the fan clutch.
Be sure air is able to come through the radiator (i.e. condenser is clean) and you have the late style plastic fan. I think it is white.
If you have never removed the fans for cleaning around them, go ahead and do this. Be prepared for lots of **** to come out.