My ac was cooling good then it started blowing hot air then blowing cold air and now the outside unit comes on for few seconds cuts off and on for few seconds cuts off

Bootsie, call an ac specialist and get it fixed.

Im going to have to agree with tickle on this one. Going to be hard to trouble shoot online. If you are handy with a voltmeter, and have a decent knowledge of the components and workings of the unit, you could check things out one by one. Could be a great number of things happening here.

If the fan is not running is the compressor not running also... if neither is running the possible reasons are 1.. no power to outside unit... 2.. bad contactor on outside unit.is this buzzing if it is this indicates no power... 3 bad capacitor,do both compressor and fan humm then quit humming and hum some more... 4 high pressure switch has shut unit down because fan wasn't running if compressor was running but not fan... if your unit has this there will be a manual reset button where the lines come out of unit... if compressor was running and fan was not... 1 bad fan... 2 bad capacitor.. if you do not have any electrical knowhow I would recommend calling a hvac tech to come and fix unit.