I would test those sensors first, I doubt that both went bad at the same time. I would suspect the wiring or the VDM. The best way to test it is with the proper scan tool.
I misspoke about that tool though, It is not the DRBII for the Ford/Lincoln/Mercury line, Had a different vehicle on my mind, Sorry. F/L/M uses the IDS tool.
The scan tool can make the VDM enter a self test mode where it tests the sensors and itself.
To test the sensors on the vehicle you will need a multi-meter and either some back probe pins (dressmaker T pins work good for this) or some insulation piercing probes (just seal the tiny hole with some liquid electrical tape)
Disconnect the actuator levers from the arm. You will be moving the sensor arm itself. Remove fuse 111 (powers the compressor, you do not want the thing to suddenly pop into the air while you work on it)
Pick a sensor. Both sides use the same colors for ground and power. Ground is a black wire with a pink stripe and power is the red wire with a black stripe.
The left side uses a pink wire with a black stripe as the signal wire, the right side uses a Tan wire.
On the ground wires you should see no voltage when the system is on.
On the power wires there should be a constant five volts.
When you test the signal wires, connect one side of the meter to ground and the other to the wire. As you move the sensor arm the voltage should smoothly increase and decrease from about.50 volts to about 4.5 volts.
If you lack the power signal verify that fuse 30 and fuse 27 are OK. If they are then locate the VDM and test the same colors there, That way you can find out if it's a broken wire between the VDM and the sensors.
If you lack the ground side check the ground connection for the VDM, it is behind the left kick panel in the drivers foot-well. Check it at the VDM as well.
If the sensors test okay re-connect the arms and move to the air solenoids.
These are nothing but simple coils. The black wire grounds the front ones at the right side of the radiator (where the compressor also grounds so maybe check that first as rust/broken wires could be causing both issues) and the other wire powers them. To test them, unplug them and simply run a pair of jumper wires down and touch the terminals on the solenoids. Do not hold the wires on them, you are just testing them, a quick click should mean they are Okay.
If they test okay re-connect them and move to the compressor relay, From it you can test the compressor. Plug fuse 111 back in. Check the relay, it should have twelve volts at the light blue with pink stripe, ground at the black wire. The gray wire with a red stripe carries power to the compressor. The dark blue with yellow stripe is the on/off signal from the VDM. If you apply twelve volts to the gray wire with red stripe the compressor should engage and pump air.
You have now tested every part but the VDM, Hopefully you found the bad ground or power connection causing the problem. Otherwise you will need to get to a dealer and see if they can scan and test the VDM.
The wiring diagram might help.
Images (Click to enlarge)
Thursday, January 3rd, 2019 AT 6:28 PM