You don't. IF it wasn't installed at the factory it would cost above and beyond what you would want to spend. I'm not saying it's impossible, but danged near.
What is the air conditioner layout in a 1999 ford escort?"
No
The 2002 Ford Escort zx2 does have an air intake air temperature sensor. The sensor is at the top of the engine on the drivers side.
no
It has no cabin air filter.
On the air intake.
You will find the mass air flow sensor INSIDE the round plastic housing between the engine air filter and the engine air intake tube on your 1998 Ford Escort ( you can see where the wiring connects )
go to autozone.com
It is in the right half of the engine air cleaner.
It doesn't have one.
controls the fuel and the air conditioning
The air filter on a Ford Escort ZX2 is changed by opening the latches on the air handler box and lifting up the top cover. The old filter can then be removed and a new filter put in place.