The MARS 19166 Potential Relay is a specialized HVAC compressor start relay designed for demanding capacitor-start induction-run (CSIR) and capacitor-start capacitor-run (CSCR) motor applications. Operating at a 395V continuous coil voltage with a robust 35-amp contact rating, this Type 166 potential relay accurately monitors back-EMF to precisely manage start capacitor dropout. Engineered as a universal replacement relay, it features a non-positional mounting design and a break-off universal bracket, allowing for seamless installation in tight control boxes across various air conditioning and refrigeration systems. For technicians performing a hard start kit installation or a compressor relay replacement, the MARS II 19166 provides reliable switching performance with a pick-up voltage range of 204-233V and a drop-out voltage of 60-121V. This industrial-grade potential relay ensures that the start winding is efficiently energized during high-torque startup while protecting the motor from capacitor-related failure by disconnecting the circuit as the motor reaches operating speed. Its cULus approval and Class B insulation make it a standard choice for HVACR motor protection and single-phase motor troubleshooting. Key Benefits: High-Current Capacity: Maintains a 35-amp contact rating at 480 VAC, suitable for heavy-duty commercial refrigeration and residential HVAC units. Universal Mounting Logic: The non-positional design and snap-off bracket simplify field cross-reference for thousands of OEM models. Precise Motor Control: Optimized for 395V coil voltage to ensure high-accuracy capacitor switching based on motor back-EMF. Efficient Wiring: Includes a wiring diagram and QC-6 kit to easily convert from screw-on to push-on terminal connections. Common Questions: Can I use the MARS 19166 as a universal HVAC potential relay? While it features a universal bracket, you must verify the pick-up and drop-out voltage specifications match the original OEM part to ensure the start capacitor disconnects at the correct motor speed. What are terminals 4 and 6 used for? On the MARS 19166, terminals 4 and 6 are "dummy" terminals used for wire anchoring and have no electrical connection to the internal relay coil or contacts. How do I test this relay in the field? Use a multimeter to check for continuity between terminals 1 and 2 (normally closed contacts). A resistance measurement between terminals 2 and 5 will verify the integrity of the relay coil. This item is not eligible for free shipping. Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.
