A/C went hot engine light came on Code P0128. Bad termostat maybe?

The code is for a thermostat. Not sure how that relates to the AC. Two separate systems. I'd check the coolant level, maybe replace the thermostat and check the refrigerant level in AC.

I have that problem. But my engine light never came on but my a/c goes on and off. I have had my compressor changed and thermostat. Both have not fixed the problem.

If your coolant temperature sensor does not give a reading, it will not allow for the A/C compressor to turn on. I was told this by a mechanic because that'[s exactly what's been happening to my car. I too was under the impression that it's not a related issue. I was wrong. Some kind of protection feature keeping from further damage to your motor.