* Power Wire (usually heavy gauge): This provides the 12V power to run the compressor clutch. It's often a large gauge wire, sometimes fused separately. It may be directly from the battery or through a relay.
* Ground Wire: A good solid ground connection is essential. This is usually a bare or black wire to the chassis.
* Clutch Control Wire (smaller gauge): This wire carries the signal from the AC system's pressure switch and other components (like the cycling switch, temperature sensor, etc.) to engage or disengage the compressor clutch. This is often a thinner gauge wire.
Finding the Wires:
The best way to identify the wires is to:
1. Consult a wiring diagram: A factory service manual for your specific year and model K2500 will be invaluable. These diagrams show wire colors, locations, and functions. You can often find these online through sites selling repair manuals (like Helms).
2. Trace the wires: Carefully follow the wires from the AC compressor to their connections. Look for any connectors or splices near the compressor. You may need to remove some underhood covers or shrouds to get a clear view.
3. Use a multimeter: If you are comfortable with basic electrical testing, a multimeter can help you determine which wire is power, ground, and the control wire. Remember to disconnect the battery negative terminal before testing!
Caution: Working on AC systems involves high pressures and refrigerants that can be harmful. If you are not comfortable working with automotive AC systems, it's best to have a qualified technician perform any repairs or diagnostics. Improper handling of refrigerants is dangerous.
