1993 Mercury sable, black box near radiator buzzing....

It is located next to the engine thermostat which is at the end of the upper radiator hose on the engine.

The 3.0 engine should be near the crank pulley in front of the engine.
The 3.8 engine uses a distributor.

There is a drain **** on the driver's side on the bottom of the radiator. It is hard to reach and hard to see. You'll probably need to remove the black cover under the radiator and bumper to get to it.

The MAF or mass air flow sensor is located on a tube connecting the air filter box to the throttle body. Just unplug the connector and unscrew the sensor then pull it out.

clean all connectors and take jumper wires from battery and connect to diconnected fan while moving the wires to determine which wire may be bad. Sensor may be higher temperature trigger or the cars temp sending unit may be misreading..

don't know what the silver box is, but its probably the transmission cooler line going from tranny to radiator. should be 2 silver lines coming from radiator. follow them

Replace the 'lift assist' hydraulic pistons (one on each side), available at parts stores.

The relay for the air conditioner compressor is located in a black box on the radiator support. this is a multi-function relay box and is sealed. This box has a large bundle of wires plugged into it. This controls the fuel pump, A/C compressor, and cooling fans. Unfortunately, the whole thing will have to be replaced which will cost around 100 dollars unless you can find one in a salvage or junk yard.

On the battery neg cable you will see 2 small wires going to a gray connector. Cut the connector out and re-splice the wires.

does the car make a squeking noise when you start it?