taurus fan control
The po had installed a couple of the cheap (cheap made but not cheap $) fan controllers on my rig. I never trusted it to protect my engine in fact the low speed never worked (fried). I spent a lot of time reading and did not like most of the systems I saw. I went with the keep it simple approach using Horton temperature switches in the manifold and head and used the tyco 75 amp motor relays. I run a 160 F thermostat, the fan should come on 20 deg above the thermostat setpoint. The low speed control comes on at 185 F, the switch is in the intake manifold, the switch picks up one of the 75 amp relays. The high speed comes on at 195 F, the switch is in the head, it picks up a 30/40 amp cube relay that drops out the 75 amp low speed relay and picks up the high speed 75 amp relay. The horton switches are very high quality and are used on large truck type diesel engine electric fan clutches. I picked them up for $15 each on ebay (normally about $50 ea). The 75 amp tyco relays are made for running inductive type loads such as the fan motor, I picked them up for $17 each on ebay. I used a couple 40 amp 12 v breakers from autozone for overcurrent protection. 99% of the work is done by the very robust low speed horton switch and 75 amp relay, with the other switch and relay in reserve. Although not elegant, it is very robust and will last for years. I don't like messing with this stuff over and over when the solution is so simple. If you like, I can send pictures and the schematic details.
