searcyfarms Thank you so very much sir for all your help. My dealer talked about changing the thermostat this week. I will post if that has solved my problem. Now searcyfarms like I said in my first post, I put the tractor back in medium and number 1 in the gears, and I had to open all the windows like I have had to do many times before, but with the ac off I was able to completely cut all 6 acres of grass around my house with the temperature now just below 1/2 and no over heating. As for the 48 HP-PTO my dealer sold me the 12 ft. bush hog and it has worked great for the past 4 years without any problems in over heating or anything else. You asked about contamination of the system, My dealer takes care of my tractor for me, because I have Polio and its everything I can do just to pull myself up into my tractor with the help of a 2 step ladder. The AC does cool good right from the start.
Whatever increased load/reduced air/water that has changed in the tractor is small enough that it takes time to get things heated up - as temps cool I bet you find it will take longer to heat up as well.
Answer, once my tractor gets hot, even after I get the temp down to 1/2, it will heat right up quickly if the ac is turned back on while cutting my grass.
searcyfarms I am not sure about the water pump. I did ask my dealer about that. As far as the belt, in July my tractor got a new belt when the fan was replaced, and that is when all this over heating problem started. Again I thank you searcyfarms for all your patience with me and for all your help.