Can a bad contactor damage a compressor?

Yes, a severely faulty, pitted, or stuck contactor can cause catastrophic and expensive damage to your air conditioning compressor. If the contactor's copper points become severely pitted or burnt, they can introduce high electrical resistance into the circuit, causing voltage drops that starve the compressor motor of the steady electrical voltage it requires to operate safely. This voltage starvation leads to severe overheating of the motor windings. Furthermore, if a faulty contactor's mechanical plunger becomes stuck or fused in the closed position, it will supply continuous power to the compressor, forcing it to run indefinitely without shutting off, which can overheat the system, trip internal thermal overloads, or burn out the motor. You can troubleshoot by inspecting contactor points. You can verify system safety when replacing a worn contactor restores normal, controlled switching.