My husband did a complete tune up on are caddy. We took our daughter to her softball game everything was fine. Later that day took the car on the highway and it started to over heat. It said Engine hot a/c off and then the car shut off. We let the car cool down got off the highway and went back home. All the way home the car was fine. The next day my husband replaced the theromstat. Took the car for a test drive on the highway and the same thing happened. He let the car cool off and got off the highway and the rest of the way home the car was fine. My husband added stop leak into the coolant because the car has been losing alot of anitfreeze. and he thought that would help. But the anitfreeze is not leaking either. Does anyone know what the problem could be?

Thanks for your help,
Shanna

 

try this ...
https://www.cadillacforum.com/m_7193/tm.htm