PLEASE HELP A MAN OUT

[myfordfusionsucks]

Hello, I have a Ford Fusion 2013 4cyl ecoboost turbo 1.6L and been running into a over heating issue with it. I will start off by saying I know nothing about cars, and bought the car about a year ago. When I bought it was in the middle of winter so had no sign of overheating, but the first time i turned the ac on and drove 20 minutes, the temperature gage slowly crept up. This has been happening ever since and if i ever turn on the ac, within 10-20 minutes of it being on it will overheat. It will overheat faster when idling or going up a hill. Usually it will return to normal levels with the ac off, but it will occasionally even overheat without the ac on if im driving it for long enough. I brought it into the shop to have them fix this issue. They replaced the radiator, a sensor expansion valve, and the water pump but after getting my car back it was still over heating. I took it back in and the mechanic has had it for over 2 weeks now and says he literally cannot find what is wrong with the car. He says the last thing to replace would be the thermostat but also said he doesnt know for sure if thats the issue or will fix it. Im already 800 dollars in on repairs and really dont wanna drop another 600 for something that might not fix it. As a broke college student I also dont have the funds to buy a new car right now, and dont wanna sell it and scam someone else out of their money. I really need some help, has anyone experienced this or know what i should do. Thank you please ask any questions about it you may have.

[WKelley]

The 1.6 was not a good engine and they have headgasket issues.  Compression test and leakdown tests need to be done.  They should also be testing the coolant for exhaust gasses.  They can scope the cylinders as well and look for one to be really clean compared to others.  I would not spend another dollar without proper testing getting done.