Is it hard on a car to start the engine with the air conditioner in “on” position? Also, is it bad to start the car by leaning across the passenger side to turn the car on?
No and no
No, and no.
The AC and other accessories are turned off when you turn the key to the start position. The AC compressor does not engage until after the engine reaches idle speed.
The car does not care from which seat you turn the key. Just don’t reach through the steering wheel to do it.
Here’s another vote for two “nos.”
Neither of these things will harm your car, regardless of where you live.
No on the AC. The clutch that connects the compressor to the crankshaft is electrically controlled and its circuit is not enabled when the key is in the “start” position. Even if the AC is “on”, the compressor is not engaged until the key is released to the “run” position.
No to leaning over to start the car. Modern cars do not have to have the gas pedal depressed to configure the fuel metering system for starting, so the car doesn;t care where the person starting the engine is sitting. Your back might “go out”, mine would, but the car will be fine.