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Dewitts Dual Fan Control using the Derale Adjustable Dual Electric Fan Controller
I recently had a Dewitts Radiator with Dual fans installed to help address some high on track temperature and it works great. The installer wired both fans to be on all the time which is fine for the track but a bit noisy for cruising and it was taking a while to get the engine up to temperature with the polar vortex summer.
The Derale Adjustable Dual Electric Fan Controller (#16788) adjustable from 150°-240°F is capable of controlling two separate 35 amp fans at different turn-on temperatures, with only a single probe.
The first electric fan will be activated at the temperature set by the user followed by the second electric fan when the temperature becomes 10°F warmer. Each electric fan will turn off at 10°F below its turn-on temperature.
An override connector allow turning on the first fan with the AC activates or can be used as a manual switch.
Kit comes complete with wiring harness, circuit breaker, all necessary electrical connectors and push-in style radiator probe.
Design and construction quality are good. Electronics are encapsulated and dual 35 amp relays are used to switch power. The dual fans require 13 amps each so plenty of margin in the relay rating.
I inserted the thermistor probe just above the radiator intake hose on the drivers side, this is the hottest side of the radiator.
Temperature adjustment is via a multi-turn potentiometer set at 185 to start. Adjustment resolution is 3.5 degrees per turn.
The kit come with a 50 amp circuit breaker that is much higher than needed for the two 13 amp fans so I replaced it with a 30 amp in line fuse for a little cleaner install.
Last edited by StKnoWhere; 08-09-2014 at 11:24 PM.
I recently had a Dewitts Radiator with Dual fans installed to help address some high on track temperature and it works great. The installer wired both fans to be on all the time which is fine for the track but a bit noisy for cruising and it was taking a while to get the engine up to temperature with the polar vortex summer.
The Derale Adjustable Dual Electric Fan Controller (#16788) adjustable from 150°-240°F is capable of controlling two separate 35 amp fans at different turn-on temperatures, with only a single probe.
The first electric fan will be activated at the temperature set by the user followed by the second electric fan when the temperature becomes 10°F warmer. Each electric fan will turn off at 10°F below its turn-on temperature.
An override connector allow turning on the first fan with the AC activates or can be used as a manual switch.
Kit comes complete with wiring harness, circuit breaker, all necessary electrical connectors and push-in style radiator probe.
Design and construction quality are good. Electronics are encapsulated and dual 35 amp relays are used to switch power. The dual fans require 13 amps each so plenty of margin in the relay rating.
I inserted the thermistor probe just above the radiator intake hose on the drivers side, this is the hottest side of the radiator.
Temperature adjustment is via a multi-turn potentiometer set at 185 to start. Adjustment resolution is 3.5 degrees per turn.
The kit come with a 50 amp circuit breaker that is much higher than needed for the two 13 amp fans so I replaced it with a 30 amp in line fuse for a little cleaner install.
looks good however you may want or need to change the power supply to take it's power from a relay controlled by the original fan controler.
the reason being tha above 40 mph the fans actually hinder air flow. so they are shut off, saves power and increases cooling at speed
looks good however you may want or need to change the power supply to take it's power from a relay controlled by the original fan controler.
the reason being tha above 40 mph the fans actually hinder air flow. so they are shut off, saves power and increases cooling at speed
Thanks, I like the idea but my understanding is the C6 does not have a fan relay but they are electronically pulse modulated controlled by the ECU?
I was told the dual fans draw too much current for the stock PWM controller?
yes that is true although I believe the fan power from the controller would work a relay that would keep the other controller from sending power to your fans
yes that is true although I believe the fan power from the controller would work a relay that would keep the other controller from sending power to your fans
Since the controller is pulse width modulated (to vary the speed of the stock fan), there will be times when it is supplying fractional levels of voltage where the average voltage will not close a relay.
The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal.
The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal.
Cooling fan speed is effected by many different conditions and can be adjusted from 10 percent to 90 percent duty cycle (PWM), 90 percent is considered high speed fan. When multiple cooling fan speed requests are received the ECM uses the highest cooling fan speed of all the requests. The ECM commands the cooling fan ON under the following conditions:
• Cooling fan duty cycle starts when engine coolant temperature reaches approximately 95°C (204°F) and reaches high speed at temperatures above 113°C (235°F).
• Cooling fan duty cycle starts when A/C pressure reaches approximately 1100 kPa (160 psi) and reaches high speed at A/C pressures above 2480 kPa (360 psi).
• At engine oil temperatures above approximately 150°C (302°F) the cooling fan duty cycle will be commanded to high speed.
• At transmission oil temperatures above approximately 132°C (270°F) the cooling fan duty cycle will be commanded to high speed.
• After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 113°C (235°F) or the A/C pressure is greater than 1720 kPa (249 psi) the cooling fan duty cycle is set to 50 percent, low speed. If the coolant temperature drops below 110°C (230°F) and the A/C pressure drops below 1660 kPa (241 psi) the fan will shut OFF. The fans will automatically shut OFF after 2 min. regardless of coolant temperature.
I was told the dual fans draw too much current for the stock PWM controller?
I have never tested the current, but I have never had an issue running the dual fans with the stock controller. I seem to remember reading somewhere that they draw a similar amount if not less than the stock one.
Since the controller is pulse width modulated (to vary the speed of the stock fan), there will be times when it is supplying fractional levels of voltage where the average voltage will not close a relay.
The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal.
The engine cooling fan is a variable speed fan. The engine control module (ECM) controls the fan speed by sending a pulse width modulated signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal.
Cooling fan speed is effected by many different conditions and can be adjusted from 10 percent to 90 percent duty cycle (PWM), 90 percent is considered high speed fan. When multiple cooling fan speed requests are received the ECM uses the highest cooling fan speed of all the requests. The ECM commands the cooling fan ON under the following conditions:
• Cooling fan duty cycle starts when engine coolant temperature reaches approximately 95°C (204°F) and reaches high speed at temperatures above 113°C (235°F).
• Cooling fan duty cycle starts when A/C pressure reaches approximately 1100 kPa (160 psi) and reaches high speed at A/C pressures above 2480 kPa (360 psi).
• At engine oil temperatures above approximately 150°C (302°F) the cooling fan duty cycle will be commanded to high speed.
• At transmission oil temperatures above approximately 132°C (270°F) the cooling fan duty cycle will be commanded to high speed.
• After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 113°C (235°F) or the A/C pressure is greater than 1720 kPa (249 psi) the cooling fan duty cycle is set to 50 percent, low speed. If the coolant temperature drops below 110°C (230°F) and the A/C pressure drops below 1660 kPa (241 psi) the fan will shut OFF. The fans will automatically shut OFF after 2 min. regardless of coolant temperature.
yes exactly but i believe it would work a relay just fine if you want to try it is easy to do, cheap and might work well
I have never tested the current, but I have never had an issue running the dual fans with the stock controller. I seem to remember reading somewhere that they draw a similar amount if not less than the stock one.
Dewitts just confirmed it's OK hook up to the PWM Controller, not sure where I got my signals crossed on this one.
08-09-2014, 11:06 PM
Dewitts Dual Fan Control using the Derale Adjustable Dual Electric Fan Controller
