Engine Cooling problem
2003 Range Rover V8 All Wheel Drive Automatic 63000 miles

Just recently had to replace the transmission in my 03 Range Rover with only 63k miles. Picked it up, drove it about 20 miles with A/C on. Then went up a huge hill in 95 degree weather, car starts overheating. Turned A/C off and temp immediately goes down. Would the replacement of the transmission have possibley been the cause of this happening?? Is the replacement of a tranny near coolant lines that could have been damaged during the repair?? Seems odd, no problem before iin shop. Just get car out and this problem shows up 2 hours after picking up car.