Have a clicking noise, intermittent, from behind glove box area, not affected by fan speed

behind the glove box is where your blower motor is located, it sounds like the fan may be broken or something may be lodged in the area causing the noise. i expect it is the fan itself, they have small clips on them for balancing and it may be loose, as the speed of the fan increases, force stops the clip from moving.

I am assuming the noise happens with the key switch on or the engine running.
It could be a relay or one of the blend doors for the HVAC. You'll have to get behind the glovebox to find the source.

while clicking is happening place your hand on the heater blower motor and you will feel it coming from there. change the blower fan.

Remove the glovebox liner end check it out, There might be a mouse in the house,

no start and door locks are consistent with security system activation. Is your security light blinking? Are you using the factory key with the resistor on the blade? Do you have another factory key you can try?
Not sure why the blower would be affected. Does the radio work? If not, check the radio fuse inside the car, as I think it runs the blower controller. Also check the HVAC fuse under the hood--#29--this one affects the security light.
I think the body control module is behind the glove box, but not sure why it would be clicking in these circumstances.
Let me know what you find out and if you have questions along the way.

it is relays that are behind your glove box,,,,

this may be a solenoid clicking behind the glove box remove the glove box and you will find the relay thats clicking

the motor that opens the vent is stuck. Put in it fresh air mode. the vent should be on the pass side behind the glove box. Take off the glove box and disconnect the motor and replcae it. Or the cheap way is to not use that mode

If you want to solve your problem, click on the link I attached
Ford Expedition 1997 2002 Workshop Service Workshop repair manual Download

MIKE.
#1) YOU PROBEBLY HAVE A BAD BLOWER MOTOR OR POSS. A BURNT CONNECTION @ THE MOTOR. IF THE FAN WORKS ON ALL SPEEDS EVEN INTERMITTENTLY. THEN THE BLOWER RESISTOR IS OK WICH CONTROLLS THE VOLTAGE TO THE MOTOR TO GET THE DIFFERENT SPEEDS. WHEN THE RESISTOR BURNS OUT THE FAN JUST WON'T WORK ON CERTAIN SPEEDS. THE "RELAY" IS ONLY USED FOR HI-SPEED FAN USE. TRY HITTING THE MOTOR WHEN YOU GET IT NOT TO WORK AND IF IT STARTS THN YOU HAVE A BAD MOTOR.

#2) THE NOISE YOU HEAR WHEN TURNING THE IGN. ON AND OFF IS PROBABLY THE DEFROST DOOR CONTROLL ACTUATOR/MOTOR WICH HAS A POTENTIOMETER IN IT THAT TELLS IT WHEN TO STOP MOVING AS IT REACHES THE CORRECT POSITION. WHEN YOU TURN THE KEY OFF IT BY FEDERAL LAW HAS TO RETURN TO THE DEFROST POSITION IN CASE OF FAILURE. THE LITTLE SPLINES IN THE MOTOR OR ON THE SHAFT CAN GET STRIPPED WHEN THIS HAPPENS. TRY DUPLICATING THE NOISE BY SELECTING THE DEFROST ON AND OFF WITH THE KEY ON.
I WILL CHECK FOR YOUR FEEDBACK LATER