Thermostat Sensor Arcs to condensor discharge line

[TXhomeowner]

Have American Standard Alliegence 14, the heat pump thermostat sensor that connects to the freon discharge line of condensor arcs and blows fuse when turned on. I have tested the sensor and confirmed the short connection at ambient, along with measuring case to ensure not shorted to case. All checks out. My guess is the 40Amp 1-Pole Contactor 24V coil, contactor that the sensor plugs into is defective. Does this make sense? Would like to confirm before spending $70 on the contactor thank you very much.

[hvacwiz]

contactor should only cost you 15-25 $ if its more than that someone is making a big profit.