Ammonia and oven cleaning

Factual Questions
1

On the DIY show the woman tells me leaving ammonia in a dish/bowl overnight in the oven should make the oven cleanup fairly easily.

She recommends warming the oven to 150 F-then placing a container of boiling water under it.Turn off oven-presto! easy wipeup in morning.

Another site (edu.com) says about the same but putting dish into ** cold** oven.

Who’s right?What about noxous/poisonous fumes?

Anyone know the **Straight Dope? **

2

A warmed oven should make more of the ammonia evaporate. It’s only when that happens that it can combine with the grease etc. on the walls of the oven. Things will take a bit longer in the cool oven, but you avoid the possibility of getting things too warm and releasing a cloud of ammonia gas into your kitchen. 150 °F shouldn’t be a problem.