2 PCS Electric Fan Relay Kit, Dual Electric Fan Relay Kit

ecocstm Dual Electric Fan Relay Kit is a complete 2-relay wiring solution that automatically runs two cooling fans at 185°F and turns them off at 175°F for reliable engine temperature control.

This plug-and-play kit supplies two 40A relays, OE-style thermostat switch, heavy 14AWG wiring, and all connectors needed to replace worn fan harnesses or add a thermostatic control to aftermarket fans. Built for 10–16 inch cooling fans and heavy-duty use, the kit combines a waterproof, high-temperature housing with a clear wiring layout so both DIY enthusiasts and professional installers can complete the job quickly and confidently.

How does the kit control fan temperature and protect the engine?

The kit uses an OE-style thermostat that closes at 185°F to energize the relays and opens at 175°F to cut power, creating an automated on/off cycle that responds to coolant/exhaust heat. Because the thermostat is mechanical and mounts to the cylinder head or water jacket, it senses real engine temp rather than air temperature alone. Proper earthing of the thermostat and engine chassis is required for correct switching.

• Thermostat activation: 185°F on, 175°F off for consistent cooling.
• Mounting: fits cylinder head or water jacket for accurate sensing.
• Safety: requires proper grounding to the engine chassis.

What components are included and how do they simplify installation?

The kit ships with two complete relay harnesses, two 40A relays, fuse holders with 20A fuses, pipe-thread adapters, ring terminals and wire connectors so you avoid sourcing parts separately. Color-coded wires correspond to battery, ignition, fan positive, and switch signals for straightforward wiring according to the supplied diagram. The 14AWG PVC-wrapped wires and waterproof relay housings mean fewer worries about heat damage or corrosion in engine bays.

• Two 40A relays with sealed housings for durability.
• Includes two 3/8" to 1/2" adapters for thermostat mounting.
• Fuse holders, 20A fuses, ring terminals and connectors ready out of the box.

Which fan sizes and vehicle types are compatible with this relay kit?

This wiring kit supports 10-, 12-, 14- and 16-inch electric fans and is designed to suit a wide range of passenger cars, trucks and custom cooling setups. It works well as a direct replacement for factory harnesses or when installing aftermarket fans on street or light commercial vehicles. For high-current or multi-fan systems beyond two fans, consider a higher-amperage solution or additional relay kits.

• Fan compatibility: 10"–16" electric fans.
• Vehicle use: cars, trucks, performance and replacement harnesses.
• Limitations: two-relay design best for up to two fans at 40A each.

How is safety and longevity addressed in the design?

The harness uses 14AWG wire with copper conductors and PVC sleeving to resist heat and maintain flexibility; sealed relay housings are made from high-temperature nylon to keep moisture and oil out. Inline fuses protect the circuit from shorting and the included ring terminals ensure secure battery and chassis connections. Proper installation, routing away from extreme heat sources, and firm grounding maximize service life.

• 14AWG copper wiring for strong conductivity and stability.
• High-temperature nylon relay housings and waterproofing.
• Inline fuses and quality terminals for circuit protection.

Who is this for: The ecocstm 2 PCS Dual Electric Fan Relay Kit is aimed at DIY mechanics, auto shops and vehicle owners who need a reliable thermostatic control for one or two electric fans. It’s ideal for replacing faulty fan wiring, upgrading cooling on hot-running engines, or adding a thermostat-driven fan control to aftermarket radiators. If you need a packaged kit with relays, fuses and mounting adapters that’s built to withstand engine-bay conditions, this kit delivers a practical, easy-to-install solution.