A/C blows cold then warm

You have to first of all duplicate the problem. Look to see if clutch is engaged when happening, if it is then suspect system is freezing up, if drier has not been changed then replace and let sit on evac for at least one hour and check for leaks. If not engaged then have to trace down loss of power or ground at clutch.

Thanks for the response. Been observing the car for the past few days, pulling over every time it blows warm air, noticed that the condenser fan (just replaced recently)is not moving and compressor clutch is not engaged. I just find it hard to believe that my AC clutch is already done knowing that I just changed it almost two years ago, (one year and ten months to be exact) in which the mechanic told me that it is that is causing the problem. I read from some threads/topics that an AC clutch has a shim and sometimes it can cause the clutch not to function/engage well depending on the wear that it has. I checked the diagram of my car's compressor/clutch and saw that there is a shim on it. Do you guys think that this might also have something to do with the this kind of problem? Also, the big question that really boggles me is, how is it that the problem only takes place during the outside temperature is hot?

The clutch will engage more and work more the hotter the system is based off of ambient temperature. Sensors read inside temperature and react accordingly. The shim that is in there may be the wrong thickness and when the clutch is worked repeatedly the problem gets worse. Measure the air gap and compare to spec to see if gap is correct between back of clutch and the pulley front. There should have been multiple shims in the clutch kit that allows you to measure with feeler gauge and set to spec. Or you have a switch/sensor that is interrupting the power to clutch and fan at intermittent times.

I am not even sure if the thickness of shim is wrong. I have the whole clutch replaced when the bearing (or whatever that is that made a squeaking sound) first broke off, the replacement part is genuine and came from the dealer. That is why I just cannot accept that it only lasted for, say two years (now I am whining). I know there is nothing I could do. How long does it supposed to last by the way? I am now more inclined to believe that it is probably the shim since I already narrowed down almost everything else.
Thanks for your inputs, much appreciated. Going to bring the car to the mechanic tomorrow and tell all what you have said.

Let me know how it goes.

AC condenser fan is probably not working. It is a intermittent, thermostatically controlled electric fan located between the grill and AC condenser (radiator). Keeps condenser cool at slow/no speed. Check fan fuse and or fan relay first. AutoZone aftermarket $170.00.