Here's a breakdown of the likely areas to investigate:
* A/C Compressor Relay: This is the primary relay that energizes the compressor clutch. Its location varies slightly depending on the specific 1981 model and options, but it's usually found in the underhood fuse box or a separate relay center. Check your owner's manual or a wiring diagram for the exact location. This is the first place to start testing. You can test it by jumping the terminals with a wire (carefully!) to see if the compressor engages. *However, never jump a relay if there's a short in the circuit, as you could damage other parts.*
* Low Pressure Switch: This safety switch prevents the compressor from running if the refrigerant pressure is too low. A faulty low-pressure switch will prevent the compressor from engaging even if everything else is working. It's usually located near the A/C lines. You'll need a manifold gauge set to check the pressure. Low pressure could indicate a leak in the system.
* High Pressure Switch: This switch is a safety feature that shuts off the compressor if the pressure gets too high to prevent damage to the system. A faulty high-pressure switch could prevent the compressor from working.
* Cycling Switch (or Pressure Switch): Some 1981 Corvettes may have a cycling switch, and this is another potential failure point.
* Blower Motor Relay: While you say you're getting power to the compressor, it is important to check that the blower motor is working to confirm that power is also flowing through the other parts of the system. If the blower is not working, the compressor will not function properly.
* Other Relays in the System: The A/C system might have other relays associated with its operation such as relays for the A/C fan itself or for its controls.
* Wiring Harness: Damaged or corroded wires anywhere in the A/C circuit can interrupt power to the compressor.
Troubleshooting Steps:
1. Check the fuses: Start with the simplest check – make sure all relevant fuses are intact.
2. Locate and test the A/C compressor relay: This is the most likely culprit. If you have a multimeter, check for power at the relay's terminals. If the relay is faulty, replace it with a new one.
3. Check refrigerant levels: Using gauges and a proper refrigerant charging system, check your refrigerant level and pressure to rule out low refrigerant as the cause.
4. Inspect the low and high-pressure switches: Test these switches to ensure they're functioning correctly. You might need a manifold gauge set to do this.
5. Check the wiring harness: Inspect for any damaged, corroded, or disconnected wires leading to and from the compressor.
6. Consult a wiring diagram: A wiring diagram specific to your 1981 Corvette will be invaluable for tracing the electrical path and identifying all the components involved.
Important Note: Working with automotive A/C systems involves refrigerant, which can be dangerous. If you're not comfortable working with refrigerant, take your Corvette to a qualified mechanic specializing in A/C repair. Improper handling of refrigerant can lead to injury or environmental damage.
