I haven't seen it answered in any posts. Sorry if it was.
Should the air pump under the battery run when the car is cold as soon as you turn the key on? Or do you need to start the engine? TIA.

 

I think it comes on if the car is cold and goes off as soon as the engine starts to warm up, usually less than two minutes after starting. I've never really noticed it being on before I start the engine though. I know a fan comes on, but not sure if the air pump does or not.

 

It comes on after start up. Then runs about 2 minutes then goes off.