If I want to turn an original AFO switch (i.e. with AFO fans and power supplies) into an AFI, I simply change the power supplies and fans, but the switch chassis can remain the same? For example on a QFX5120 or EX4550-32F.
Turns out this is a bad idea, not because of warranty or support, but there are differences between AFI and AFO that go beyond how the fan is mounted.
Running the fan backward physically works, but the thermister that reads the "INLET" air temp will be at the exit point of hot air, so it will not be reading the ambient air temp.
The only fix now is to make sure the switch is breathing in cool air, which may mean reverse-mounting if its an AFI, or find some way to isolate the switch's inlets from the exhaust of other things in the rack.