Chevrolet Repair: 00 CHEVY MALIBU, 2000 chevy malibu, chevy malibu

Question
HELP! PLEASE, I HAVE A 2000 CHEVY MALIBU MY COOLING FANS WILL NOT TURN ON I HAVE CHEKCED THE MOTORS ON BOTH FANS BY DISCONNECTING THE TEMPERATURE SENSOR AND BOTH FANS CAME ON, I HAVE CHANGED ALL FAN RELAYS AND FUSES.  ALSO REPLACED TEMP SENSOR UNIT.  THE FANS ONLY COME ON WHEN I PUT THE AC ON.  ONLY AT THIS POINT, THE CAR DOES NOT OVERHEAT.  HOWEVER, IF I LET THE CAR SIT ON IDLE WITHOUT THE AC ON IT OVERHEATS BECAUSE THE FANS DO NOT COME ON.  ANY HELP WOULD BE APPRECIATED.     THANKS

Answer
Could be the fan switch is bad.  It is a thermal switch much like the sending unit.  Screws into the cooling system somewhere probably on the intake.  When you disconnect the temp sensor, the fans come on as a precaution.  Your liquid level could be low.  That could cause overheat and would tell the fans the motor is a different temp than it really is.