Dual temp sender

[H2Ogbodies]

Its far more efficient to run them both. It makes absolutely NO sense to run one fan, then the other. Having said that, I would suggest assembling a 2-speed relay harness so you can run them both in series for low and high speed. To my knowledge, no controller can be used with fans wired in series but the benefit is the simplicity of it, parts can be found at any parts store (so no worry of "design changes" or 15 versions of a controller, only to go dis-continued). And, it is a stand alone setup using GM style switches which are a proven reliable design.