Where is the current limiting diode for ac compressor located at in a 1997 buick regal gs?

There isn't a single, dedicated "current limiting diode" in the way you might think of one for, say, an LED. The current limiting for an AC compressor in a 1997 Buick Regal GS is handled indirectly through several components and the system's design. There's no one part you can point to and call the "current limiting diode."

The protection comes from:

* The compressor's internal windings: These are designed to withstand a certain amount of current. Overcurrent will cause them to overheat and fail, acting as a (destructive) current limit.

* The compressor clutch relay: This relay switches the high current to the compressor. While not a diode, a faulty relay *could* potentially draw excessive current before failing, acting as a sort of protective element, but its primary function isn't current limiting.

* The wiring harness and fuses/circuit breakers: The wiring and protective devices (fuses and circuit breakers in the underhood fuse box and/or the interior fuse panel) are designed to handle a specific amperage. An overcurrent situation will cause a fuse to blow or circuit breaker to trip, protecting the compressor and other components. This is the most likely way overcurrent is handled.

To diagnose a potential overcurrent problem, you'd need to check the compressor's wiring, fuses, and relay, looking for any signs of overheating, melting, or damage. Measuring the current draw of the compressor (with a suitable clamp meter) can also determine if it's exceeding the normal operating range.

In short: The "current limiting" is a distributed function across several safety components, not a single diode.