e46 330i overheating. Please help

I had recently purchased a 2001 bmw 330i that i toiught was in fine condition. after day 2 of driving, it started overheating. I changed the thermostat, fan clutch, radiator, and coolant resevor. i think I bleed the vehicle properly. It can blow cold ac or hot air, whichever i need. but the problem is when I change from using the ac to heat, or change from using heat to ac, the temperature will rise from normal to pass normal. Then if Change back to what ever I was using first, heat or cold, the temperature comes back down. Sometimes not all the way. Could it be the water pump? or what? any suggestions will be appreciated.



See, I used nothing but ac for two days. One early morning I took the car out and used heat becuase the weather was cold. Then it started overheating. so I was missing with it today, and figured out how when it will stars to over heat.