Sir I have chevrolet optra 2005 A/T. May engine cooling fan is not working when the AC is off. But when the AC in on it runs both. The technician advice me to have a manual switch of the cooling fan. So if ever im not using the AC my engine not oveheat. IS IT OKAY SIR? I notice both fan running slow than usaual even the AC in on. And my aircon did not make enough cool.