What is the rostra precision controls for

Under the dash where the clutch pedal would have been according to this. NOT the 100 clams one :>)

https://www.google.com/search?q=1999+ford+escort+lx+2.0+ltr+automatic+fuel+pump+relay+location

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Visit the on-line store, know as reliable-store, they have the repair manuals. I'm sure you will get the solution of your problem.
Best Manuals

yes un plug the wire and the a/c wont go on wont affect any thing else

With the engine running and hood open, is there a air sucking sound? The air intake hose which runs across the top of the engine may have a hole in it. On mine it happens in the little rubber tube which connects to the large tube. I believe it is called the PCV connector, which is on the top of the engine, towards the windsheild. The rubber part in my area runs about $5. Hope it's that simple for you.

yes they are the same part number.

you either have a clogged ac line or you have a vacuum problem that will prevent the correct vent doors to open to allow the air to enter

timing belt or fan belt

on the fuel injection engines the fuel filter is located in one of 2 places 1, under and to the rear of the engine above the drive shafts or 2, under the car at the rear just forward of the rear suspension assembly

check the vacuum diagram located under the hood this should rovide you with what you need.

right hand side under bonnet on the wing or at the back by the battery depending on model build