Good Evening Ralph, thank you for your inquiry!

I understand that the thermostat on your Frigidaire air conditioner will not cut off. I would recommend performing a reset on your air conditioner and you can do that by removing the plug and pressing the reset button on it.  Once you do that press test and you should be able to plug your air conditioner back in. If that does not help correct your issue I would suggest having a professional technician out to perform a proper repair. This will help you from purchasing multiple unnecessary parts. -OOS