Weird things going on....

I have a 2000 Gsr integra stock motor but my radiator is a civic Fluidyne dual core with a stock fan attached

If im driving my car with the heat on my temp needle stays well below the middle of the indication....even if the heat is actualy off but my temp changing switch on the center console on heat it still says well below halfway mark on temp guage

as soon as you flick it over to cool for say the ac...the temp goes up to the halfway mark really quick and you can sorta smell a little antifreeze, not much at all but a little

Car idles kinda crazy sometimes too i know i have a small vacuum leak or something im going to get a vacuum guage tommorow and do the step in the helms manual

is this my head gasket?

 

read this could be the heater core also?

 

Sounds like a leak. Let your car sit while running to find any leaks on the ground. Or try getting the right radiator.