Radiator fans working only when A/C is on

I own a 1999 malibu, the intake manifold gasket was replaced a while ago
recently I noticed that the radiator fans will come on only if I turn the A/C on if I don`t the car will overheat, if any other malibu owner out there has or had this problem and found a reason for this to happen I will really appreciate some help.

Does your instrument cluster have a temperature gauge? I was curious if it indicates the overheat condition (thinking that something might be wrong with the coolant sensor).

Yes it does have one, and it shows the temperature reading when overheats

Sorry I didn't follow that. When the vehicle overheats does the temperature gage indicate vehicle is overheating or that everything looks OK?

The thermostat on the V6 is fairly high, at 195F. The fan however, Always comes on when the AC compressor is running, which is anytime you have the AC on or the front defroster is on. The thermostat on the I4 is 180F which is fairly low. Either way, is the temperature gauge getting into the red zone ? Remember, the thermostat won't even pop until you get to 195 on the V6 which is past the middle mark. The fans come on when the gauge is about 2/3s to max if the thermostat opening isnt enough.