There's a switch on the rear control panel in the SD70MAC's cab that's labeled "Fresh Air Make Up Blower." It's right next to the Engr/Hlpr aux cab heater switches, so I'd assume it's related to the heating/cooling/ventilation system, but I wanted to confirm this before I get hot sitting in the cab one day and flip it on only to find the engine overheat and burn up or something. I saw it when I was deadheading back home a few days ago in the trailing unit on an overnight freight but forgot to ask someone on the crew (I'm a new brakeman).
Can't find any info anywhere on the 'Net: Google returns two results for "Fresh Air Make Up Blower" in quotes and a million unrelated ones (even with the words "EMD" or "locomotive") without quotes.
If it is for fresh air into the cab (which seems likely, especially with some human factors stuff on cab ventilation I found from the FRA), is it interconnected to the heating/ventilation system accessed through the computer control panels? Can that system be off while the fresh air make-up blower pumps fresh air into the cab separately?
While I'm on the subject, I might as well ask what some of the other non-obvious switches do. I'm sure I'll learn them when they get around to teaching me how to be a hostler, but I'm a curious person. How about the "Gen Field" switch? Seems like a generator is something you'd want to be on, but I rarely see it on, and I've been too intimidated to ask about it. Must not be what I'm thinking. Anything else I should know?
Thanks! Looks like a fun forum here.