drs120new Posted September 3, 2016 Report Share Posted September 3, 2016 I am having an overheat, and A/C problem, with my 2007 Lincoln MKX. I have isolated the problem down to the cooling fan system but need help in how to troubleshoot/isolate down to the cooling fans, Fan Control Module, and PCM components. I just don't want to go out and buy/replace parts only to find out it is something else. Any suggestions, links, pictures, etc ? Quote Link to comment Share on other sites More sharing options...
akirby Posted September 3, 2016 Report Share Posted September 3, 2016 Look for autom8r's topic on cooling fan replacement. The fan assembly includes the fans and controller. Beware aftermarket parts - sometimes they don't work. 1 Quote Link to comment Share on other sites More sharing options...
WWWPerfA_ZN0W Posted September 3, 2016 Report Share Posted September 3, 2016 Both radiator fans should run on full with MAX A/C engaged. If they are not, that would be the problem right there. Replacements should work perfect if Motorcraft (fan & control module). If you decide to go with aftermarket, I would at least retain the original control module in case the module that comes with the Am fans does not work. Quote Link to comment Share on other sites More sharing options...
drs120new Posted September 3, 2016 Author Report Share Posted September 3, 2016 I pulled the 2 prong plug off the FCM and put battery power to the fans directly. Fans did not spin. Took the connector off the driver's side fan, still no spin. How can I test that the output from the PCM is good? If that is OK, I'll buy a Motorcraft fan assembly from Rock Auto. Right now it looks like I need 2 fans anyway. Quote Link to comment Share on other sites More sharing options...
macbwt Posted September 3, 2016 Report Share Posted September 3, 2016 I think you have already confirmed the problem. Just need to install a new fan assembly. Quote Link to comment Share on other sites More sharing options...
drs120new Posted September 4, 2016 Author Report Share Posted September 4, 2016 It would still be nice to know if I am getting a good signal from the PCM. Quote Link to comment Share on other sites More sharing options...
akirby Posted September 4, 2016 Report Share Posted September 4, 2016 I've read about at least a dozen bad fans - never a bad pcm signal. 2 Quote Link to comment Share on other sites More sharing options...
macbwt Posted September 4, 2016 Report Share Posted September 4, 2016 Ditto on the fans. Never heard of PCM issue. Always a fan failure. 1 Quote Link to comment Share on other sites More sharing options...
autom8r Posted September 5, 2016 Report Share Posted September 5, 2016 If you have an oscilloscope lying around you can measure the signal coming from the PCM. It is a Pulse Wave Modulation (PWM) signal. You'll find that the signal is approximately 5vdc (peak) and with the oscilloscope you'll see that the cycle 0-5vdc pulses over time, increased pulse duration (width) results in faster fan speed, shorter pulse duration slower fan speed, etc. The pulse duration is interpreted by the fan control module. The tow packages module has a varying fan speed for each fan. Read the output from the fan control module connector. The signal is on the white wire with the blue stripe. +12vdc is the violet/gray and black is ground. Be careful that you don't inject signal into the PCM. There is no thermostat that controls fan operation. There is a temperature sensor at the top of the engine under the intake manifold. This device is an RTD (resistance temperature detector) and is an easy to check with a VOM. At room temperature it's about 35k ohms and at 212F it's about 2k ohms. The sensor when it goes bad causes the PCM to enter a protective mode and spool the fans up to keep the motor cool. It will also throw a DTC, most likely P0118. Make sure that the sensor is disconnected from the PCM before you read its resistance otherwise you may be reading through the PCM instead of the sensor. I am in agreement with the others on the fans. We have seen the issue here may times. You may find that buying the individual components of the fan assembly may cost more than buying the kit, fans and fan module included. There are two flavors of this fan replacement kit so make sure to get the right one. I'm not certain why your fans won't spool up on the direct 12v to the fans. I'd measure the resistance of the motors with a VOM to determine if the windings have opened or gone to ground. If you find that the motors are damaged, don't hook a new fan control module to them, the motors will fry the FCM. Best to replace it as a kit. Others on the board have had great success with Motorcraft OEM. I purchased and installed a DORMAN brand replacement for my LIMITED with tow package 70k miles ago. No issues. If you could recondition blown fan modules, you'd be wealthy. Good Luck 1 Quote Link to comment Share on other sites More sharing options...
drs120new Posted September 5, 2016 Author Report Share Posted September 5, 2016 Wow. Thank You for the in depth theory of operation. I purchased the Motorcraft fan assembly (w/o towing) from Rockauto for $230 shipped to my house. I will have it Thursday and will be installing it Friday. I pulled the 2 prong plug from the FCM and put 12 Vdc across the red and black leads. No fans spinning. Pulled the plug from the driver's side fan, still no spin. Motors obviously fried and the circuit open. Quote Link to comment Share on other sites More sharing options...
drs120new Posted September 9, 2016 Author Report Share Posted September 9, 2016 Installed the Motorcraft fan assembly today. Took about 45 minutes to remove and replace. Everything works like new now. Thanks to everyone who contributed to this thread. Buy Motorcraft and smile. 4 Quote Link to comment Share on other sites More sharing options...
PaulSchott Posted September 9, 2016 Report Share Posted September 9, 2016 I'm all for genuine ford products. I bought a replacement Dorman mirror motor. It is noisy and it is difficult to adjust the mirror because it moves to quickly and keeps going after you let go. If I needed to adjust the mirror more often, I would have junked it and used genuine. The cooling fans are important enough not to take a chance. 2 Quote Link to comment Share on other sites More sharing options...
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