Here's what you should investigate:
* Wiring Harness: Inspect the wiring harness between the compressor, the level control switch (often located near the rear suspension), and the body control module (BCM) or related control unit. Look for damaged, corroded, or disconnected wires. Pay close attention to any connectors. A broken wire or poor connection is the most likely culprit.
* Body Control Module (BCM): The BCM or a similar control unit receives signals from the level sensor and controls the compressor. A fault within the BCM can prevent the system from functioning, even with new parts. Professional diagnostics might be needed here.
* Level Sensors: The system relies on sensors to determine the vehicle's load. If these sensors are malfunctioning (sending incorrect signals), the system won't activate the compressor. These sensors are usually located on the rear suspension.
* Grounds: Check all ground connections associated with the load-leveling system. Poor ground connections can disrupt the electrical signals.
* Fuse: While less likely, there might be a fuse related to the system. Consult your owner's manual or a wiring diagram for the fuse box location and relevant fuses.
* Pressure Switch: Besides the main level control switch, the system might have a pressure switch on the compressor itself. This switch prevents the compressor from running if the system is already at full pressure. Check to make sure it's not faulty.
How to proceed:
1. Visual Inspection: Start with a thorough visual inspection of all the wiring and components mentioned above.
2. Wiring Diagram: Obtain a wiring diagram for your 1996 Oldsmobile Ninety-Eight. This will show the path of the electrical signals and help you troubleshoot specific circuits. These can often be found online through repair manuals or automotive forums.
3. Multimeter: Use a multimeter to test the voltage and continuity of the wiring, ensuring that power reaches the compressor and that the ground connections are good.
4. Professional Diagnosis: If you are not comfortable working with automotive electrical systems, it's best to take your car to a qualified mechanic experienced with load-leveling systems. They'll have the diagnostic tools to pinpoint the problem more efficiently.
Simply replacing the compressor and switch doesn't guarantee the system will work. The underlying electrical control system needs to be properly functioning. Concentrate on the wiring and the sensors first.
