Another electric fan conversion question
04-28-2017, 09:32 PM
#1
Another electric fan conversion question
My preference is electronic control (PWM), but user rating is not great. I don't want to give up my reliable clutch fan for not so reliable electric fan.
Ebay sells Crown Victoria fan control module for 2005+ for about $20. It has 2 connections. One has 2 terminals, +12V and ground, for motor connection. The other has 3 terminals, +12V, Ground, and PWM signal from ECM. Someone opened it and found IRF1404 chip, MOSFET with >100A max current capability.
My best guess is ECM sends 5V PWM signal to the module. I found a youtube video that shows the signal on oscilloscope. But I also found a conflicting youtube video (-5V instead of 5V). In either case, the person was focused on repair, not circuit analysis. I need someone to guide me to test out the module. Once confirmed suitable, I can build a simple PWM on a single chip. Or I can buy from ebay a PC fan controller, and modify it a little to generate 5V PWM.
The module has a large heat sink and is mounted on the fan shroud for adequate cooling. I don't see such a heat sink on any PWM fan controller sold for $100+. I wonder if it is the reason for low user rating.
PS: Dual fan with 4 relays is my backup plan.
Ebay sells Crown Victoria fan control module for 2005+ for about $20. It has 2 connections. One has 2 terminals, +12V and ground, for motor connection. The other has 3 terminals, +12V, Ground, and PWM signal from ECM. Someone opened it and found IRF1404 chip, MOSFET with >100A max current capability.
My best guess is ECM sends 5V PWM signal to the module. I found a youtube video that shows the signal on oscilloscope. But I also found a conflicting youtube video (-5V instead of 5V). In either case, the person was focused on repair, not circuit analysis. I need someone to guide me to test out the module. Once confirmed suitable, I can build a simple PWM on a single chip. Or I can buy from ebay a PC fan controller, and modify it a little to generate 5V PWM.
The module has a large heat sink and is mounted on the fan shroud for adequate cooling. I don't see such a heat sink on any PWM fan controller sold for $100+. I wonder if it is the reason for low user rating.
PS: Dual fan with 4 relays is my backup plan.
Last edited by paker; 04-28-2017 at 09:42 PM.
04-29-2017, 01:41 PM
#3
Thank you for the link. I think OEM design has a merit. Engine cooling control is divided into 2 parts. The part that gets hot is packaged separately (fan control module). This module is small and mounted on the fan frame (not shroud). The module is directly in the air flow path. The other part stays with PCM/ECM. Compared to OEM, DCC, Derale, and other 3rd party contollers are all-in-one. Final product is too bulky to mount directly on the fan frame. So it does not get cooled as well as OEM fan control module. I don't think DCC and Derale use inferior components. In a sense, it is unfair to them that their products get a low rating by certain reviewers.
05-05-2017, 11:02 PM
#4
This is the best youtube video I found on fan control module.
This video explains everything about fan control module. This is what I have learned so far.
It has +12V and ground connections, +5V trigger signal, temperature sensor built-in, fail-safe logic. If temperature is out of range, fail-safe is triggered and the fan runs full speed. It is practically a complete functional block.
A single wire goes from the module to PCM. +5V internal signal is connected to this wire at the module end, and PWM grounding signal at the PCM end. When PCM needs to stop the fan, it outputs ground to this wire. PCM in turn gets input from thermostat, vehicle speed, AC on/off, transmission shaft rpm, etc, depending on make/model of the car, and outputs the right pulse width modulated grounding signal.
The video is about Mitsubishi Lancer, but the principle applies to many other vehicles. It is almost funny that a fan control module for a Ford also fits a GM, and Mazda 6 (which is Ford) and Mitsubishi Lancer use the same module. This means I can go to a junkyard and get a fan/module from any vehicle and make it work on my F150. Of course, I have to build a circuit to generate pulse width modulated grounding signal. I ordered the parts for the PWM controller. Will post update later.
It has +12V and ground connections, +5V trigger signal, temperature sensor built-in, fail-safe logic. If temperature is out of range, fail-safe is triggered and the fan runs full speed. It is practically a complete functional block.
A single wire goes from the module to PCM. +5V internal signal is connected to this wire at the module end, and PWM grounding signal at the PCM end. When PCM needs to stop the fan, it outputs ground to this wire. PCM in turn gets input from thermostat, vehicle speed, AC on/off, transmission shaft rpm, etc, depending on make/model of the car, and outputs the right pulse width modulated grounding signal.
The video is about Mitsubishi Lancer, but the principle applies to many other vehicles. It is almost funny that a fan control module for a Ford also fits a GM, and Mazda 6 (which is Ford) and Mitsubishi Lancer use the same module. This means I can go to a junkyard and get a fan/module from any vehicle and make it work on my F150. Of course, I have to build a circuit to generate pulse width modulated grounding signal. I ordered the parts for the PWM controller. Will post update later.
Last edited by paker; 05-05-2017 at 11:07 PM.