my fan turns on when I start my car stays on until I get out of store

Hello, The fan can stay active until it needs to shut off. There is a limit, however. If your fan is running and the car cold and off, that is an issue. The fan has a built in resistor that will allow it to run all the time or not at all when it fails. If your fan is running for more than 30 minutes or so, there is something wrong there. Testing will require you to get the manual and follow the steps to test the fan and fan resistor.