no overdrive or ac when at operating temp please help!!

[gpabuick]

I just bought a 95 riviera supercharged with 130k from a older gentleman about 2 weeks ago. Took it for a test drive and all was good. But after driving it for about 30 min it wont shift overdrive anymore and the ac stops. The compressor wont even kick on. It runs at 200 and never any warmer.I have scanned it with a professional scanner and no codes, or check engine light. I know these transmissions can have the no overdrive problem When the valve body heats up and expands more than the valve for overdrive so it leaks past and wont shift, but it seems like the computer is stopping it from shifting and the ac from working because it thinks its overheating. Oh and also the low coolant light comes on and off at random but the coolant is full. Any inputs will be appreciated!! Is there any way to bypass something to test whats happening like a temp sensor or something? oh and the trans fluid is full and looks/smells fine.

 

[MelsRegal]

did you get the 200 temperature from the dash gauge or did you use an IR gun to confirm the gauge is accurate? The coolant level sensor needs to be changed to cure the light problem. Has the transmission filter and fluid ever been changed?

 

[gpabuick]

did you get the 200 temperature from the dash gauge or did you use an IR gun to confirm the gauge is accurate? The coolant level sensor needs to be changed to cure the light problem. Has the transmission filter and fluid ever been changed?

Got the temp from the gauge on the dash. Never smells warm. Has new radiator. I know the low coolant sensor needs changed, I just wondered if that might make the computer not let the trans shift overdrive. But the low coolant light will come on and still shift overdrive for about a half hour or so and then boom. No overdrive. No sounds/smells/lights just no overdrive. As far as the trans fluid I actually don't know.It looks/smells good. I know the cooler line had a leak the previous owner fixed.