Simple green and cleaning ac unit?

plain water out of the garden hose is fine. dog pee won't damage the coils

Water will do it but not at high enough pressure to bend the fins, the dog went once he will go again, You need to put some sort of barrier/fence so the dog is not able to piss on those fins. Dog urine can and will eventually react with the aluminum and eat it away.  I have no idea what is in simple green so I would not use it.  Ensure that whatever you use, still leaves plenty of space for airflow and for servicing the unit, you also want to keep vegetation down around the unit.

plain water out of the garden hose is fine.  dog pee won't damage the coils

Clean it with any cleaner and then rinse thoroughly. 

Tach you dog to not pee on it or you will be washing it daily. 

I'd just use water to rinse it well.   If you do use simple green don't leave it on long an rinse well. You need to fix something so the dog can't pee on it.  Dog pee will eat up the fins an cause leaks.