should both fans come on when ac is turned on, cause only one comes on know,

when I turn on ac, only one fan comes on, engine compartment(fan2) and it does'nt seem to be cooling correct, I added one can of freon, but noticed when, like idiling in traffic it starts blowing warm air,(inside car) but get back on highway and it starts cooling again a little better, when I turn the fan blower switch to High, it blows warm air, so I put the switch back to 3 it starts cooling again, I think my regular (fan1)(engine compartment) is not working because I use to hear it come on but not sure.