There is a guy that goes by the name
The Auto Cool Guy at the website
autocoolguy.com. His real name is Darryl Dashiell. Darryl is a Vietnam Vet and he builds some of the nicest electric fan and water pump controllers I have ever seen.
He built a custom unit for me that I ordered through Hollister Road Company. Sadly, the Hollister Road Company owner, Dave Chapman, passed on a couple of years ago.
This is what my unit looks like;
This was a custom build to control an electric water pump and a MK VIII Lincoln electric fan using Pulse Width Modulation (PWM) control. The fan was the biggest challenge because it drew a little north of 100 amps on a cold start. Sort of like a starter motor, unbelievably, but a fan! The high current draw would kill just about anything that was commercially available at the time.
Darryl built this unit with a soft start capability that turns the fan and pump on at a very low speed initially as the temp sensor sees the coolant temp rising both seamlessly increment in speed to maintain your target engine temp. The start temps are settable with a screwdriver and separate dashpots.
As the vehicle comes up to road speed and the airflow through the radiator is adequate to cool the radiator the fan slowly ramps down to a lower speed or zero depending on air flow across the radiator and where you set the coolant on temp threshold.
When you shut the car off the fan and water pump run on for two minutes or so after engine shut down to eliminate any hot spots in the engine.
The unit is very easy to configure and use. When you install it you remove the mechanical thermostat because it is no longer used. There is an electric coolant temperature sensor that takes the place of the thermostat and informs the controller of the coolant temperature so it can determine how fast to drive the water pump and the fan to maintain your target engine temp.
Very nice package. I suspect 99% of you guys don't / won't use an electric water pump so that part is probably a not so necessary element for your installations.
Check out his website he has a gazillion variations of just the basic fan controller system and they are all his design and made by him right here in the US and if that's not enough he's also a Vietnam vet!
Ed