Whenever I try to get Uni into the car, she will NOT jump in willingly unless she knows the a/c has been running for at least a few minutes. Even if it's not that hot, and I carry her in the car, I can feel her body trying to fight me bringing her inside.
Most of the time during the hot months, I have to start the car and turn on the a/c and TELL HER the a/c is on, then she will get in the car.
I know she's got a year round fur coat, but when we first got her, my old car didn't even have a/c! She would lay on an ice bag in the center console with the windows rolled down and she was totally fine! Now that she knows the "finer" things in life she will have no less. Oh, how I have spoiled her.