Overheating

My car is overheating with the a.c. on. The first day
it started,  the a.c kept blowing hot air. I checked
the temperature to see if it was overheating, until
later that day it started to overheat and leak out all
the coolant . From there I drove my car all the way
home without the a.c..  We then checked to see if
there was a leak (tested with water ) as I reaved up
the engine the water squirted out a streams of
water at the top of the resivor and water was
leaking from the resivor.  The engine wasn't
overheating at the time cause the a.c. was off.  
Could this be a fan relay ? Or what other
possibilities