Your engine has a very limited range of temperatures at which everything runs optimally. The problem is that for all the power your engine puts out, it releases heat as a byproduct. Consequently, your engine needs a variety of parts to keep it cool. For performance engines that put out greater levels of power, cooling demands are higher - thus the Hypertech Fan Switch. The Hypertech Fan Switch signals your engine's cooling fan to kick in earlier than normal as a proactive approach to maintaining an optimal temperature in your engine bay and keeping your engine's power output at peak levels. Without this safeguard, the excessive heat in your engine could cause the fuel to combust earlier than it should, a condition called "knock." If this occurs over a prolonged period of time, it could do severe and irreparable damage to your engine. Hypertech produces a large line of electrical devices designed to work in conjunction with your vehicle's computer to get the most power and performance out of your vehicle. The Hypertech Fan Switch is no different. It works with the timing mechanisms in your vehicle's computer, and as a result keeps your engine running a bit cooler and considerably better. All customers always deserve tremendous customer service while shopping for quality parts for their car or truck. So of course we established a 24-hour, 7 day a week assistance bureau to assist you with your needs. Everybody hates to pay for shipping, that's why your parts come with 100% free shipping for all orders $50 and higher. If you spot a lower price elsewhere, let us know - we will meet or beat any legitimate auto part price.