Radiator fan not working.

[PhoenixM3]

I have a 2018 FiST with an S280 and 50K miles. Last week in 94 degree heat and in stop and go traffic, I got the dreaded high coolant temp alarm, then quickly shut off the AC, maxed out the HVAC temperature and fan speed, and turned onto a side street to give some air flow over the radiator. Coolant temps dropped, but remained at about 220 until I got the car to higher speed, then it only dropped to 217.

The coolant fan fails to work regardless of ambient temperatures OR if the AC is on. Coolant level is fine. I checked the fan fuse, replaced the fan relay, but have yet to research/price the fan control module. The fan spins freely when the engine is off and I do have the 180 thermostat installed, but don’t think it is part of the problem. This morning, I’ll put the car on ramps and check the electrical connections on the fan control module. Am I missing any other simple check?

Ok, update. I put the car on ramps, disconnected and removed the fan control module. The connector which leads to the fan had one charred (positive) connector, so not sure if fan, control module or both had failed. Using a 12 volt power supply, to test the coolant fan, I connected the fan and it didn't work at all. To verify the fan module was functioning, I installed the module, but left the connector leading to the fan disconnected (smaller connector). I started the car, turned on the AC, and measured 14.4vdc at the terminals (on the module) which power the fan.

Tasca Ford shows a radiator fan assembly to cost about $250. Any leads on where to procure a used/or cheaper one?

Thanks,

Jeff

 

[Ford ST]

You could always go aftermarket on RockAuto, but what I have noticed is the aftermarket fans do not have the flaps like the OEM fan. The Fiesta ST uses a different radiator fan assembly than the regular Fiesta. The aftermarket parts are geared towards the regular Fiesta.

With that said RockAuto has the OEM fan assembly for $241. Look up RockAuto discount codes and put that discount code in the "how did you hear about us" box and you will get 5% off. I guarantee you the shipping will be better than the website you posted above.

Good diagnostic work by the way.

Also the OEM part does come with a new fan control module. I would probably stay with the OEM part especially with how easily these cars overheat. If money is tight you could try a aftermarket part but they do not have the flaps, and I also wonder is the fan is going move as much air.

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[PhoenixM3]

You could always go aftermarket on RockAuto, but what I have noticed is the aftermarket fans do not have the flaps like the OEM fan. The Fiesta ST uses a different radiator fan assembly than the regular Fiesta. The aftermarket parts are geared towards the regular Fiesta.

With that said RockAuto has the OEM fan assembly for $241. Look up RockAuto discount codes and put that discount code in the "how did you hear about us" box and you will get 5% off. I guarantee you the shipping will be better than the website you posted above.

Good diagnostic work by the way.

Also the OEM part does come with a new fan control module. I would probably stay with the OEM part especially with how easily these cars overheat. If money is tight you could try a aftermarket part but they do not have the flaps, and I also wonder is the fan is going move as much air.

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Appreciate the tip with Rock Auto. The flaps are on the passenger side, so I’ll try my luck with a generic fan from Summit Racing.

I still need to cycle the AC off and on to verify the output of the fan control module changes states (varying DC voltages).

I also got pricing on a used one for $95 shipped, so that’s not bad

 

[CarGuy]

I'd go with a used OEM one over an aftermarket any day.

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[PhoenixM3]

I'd go with a used OEM one over an aftermarket any day.

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Probably a wise choice. I received 2 quotes over $300 for used before I received a quote for $95.

 

[Intuit]

The harness and wire should be rated to handle whatever the module is capable of putting out.

When connectors fail, it is usually one (or more) of the following reasons:
* Harness didn't seal out air/water.
* Poor/Weak/Partial connection.
* Defective contacts - metal composition wasn't properly manufactured.

Some of that energy passing over that connection gets converted to heat. That heat accelerates corrosion. More corrosion creates more resistance and more resistance results with more heat which accelerates corrosion. It's a runaway effect.

If either one of those contact pins shows any heat-damage, corrosion, then they need to be replaced. If you replace only one or the other, it may take awhile, but you'll eventually end up right back in the same place.

I know it's possible to take apart the headlight harness and re-pin them... which means it's possible to replace them if they're damaged. If the pins on your fan-module harness are damaged, check to see whether it can be disassembled. Matching contact pins can often be found in kits on Amazon.

Make sure the seals around the harness are proper. Coat them with dielectric grease. Make sure the seals at the rear of the harness are proper. Air/water can enter from there as well.

If the pin on the module is damaged, you're kind of screwed unless you're handy enough to disassemble, replace the connector and reseal the module. Sometimes you can get away with coating the damaged pin with Radioshack's silver-bearing solder but when a contact pin is overheated, its composition changes. It'll never conduct electricity as efficiently as it used to.

 

[Ford ST]

The fact the fan would not run when applying power to it obviously says the fan is toasted. A bad fan can easily burn up the wires seen it quite a few times.

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[CarGuy]

Probably a wise choice. I received 2 quotes over $300 for used before I received a quote for $95.

Make sure the $95 is from an ST and not the base Fiesta.

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[M-Sport fan]

Once you have everything fixed and back together, I would ask your tuner to maybe program in a lower high speed fan setting (like when the coolant reaches 205*F- 210*F or so), even when the AC is TOTALLY OFF.

 

[Magnetic]

My 16 started overheating a couple months ago. I ordered the Mishimoto radiator w/fan shroud. When my mechanic was replacing it he said that most likely the issue was the expansion tank because it was ballooned and the hose fell right off when he was doing the install. I ended up replacing that too. This is just an FYI for anyone that had an overheating issue. Your case is different but I learned a bad expansion tank also causes overheating issues. (I have no idea why) I could've save $600 but I guess living in Arizona having better cooling is a good thing for canyon runs.

 

[PhoenixM3]

Once you have everything fixed and back together, I would ask your tuner to maybe program in a lower high speed fan setting (like when the coolant reaches 205*F- 210*F or so), even when the AC is TOTALLY OFF.

That is a great idea. I’ll upgrade the radiator next year anyway.

 

[Intuit]

@Magnetic - Unrelated, at least some of the 2016 STs had a campaign for the fan relay. Some had the wrong one installed by mistake at the factory. It had a lower rating and smaller contact pins. I tried to get the service dept and parts guy to just give me the part for self-install rather than kill an HOURS of my time waiting on them to schedule shop time to fondle the car, looking for selling opportunities... *cough*... I mean issues that don't exist. Wouldn't do it so I just bought the relay. Took three minutes to install it at the dealer parking lot. The cover is flexible; no need to remove the battery tie-down.

The fact the fan would not run when applying power to it obviously says the fan is toasted. A bad fan can easily burn up the wires seen it quite a few times.

Just noting that the fan cannot draw more power than it is being fed. The fan merely exposed preexisting flaw. If everything else is proper and yet it is possible for a device(s) to burn up the wiring and/or harness, then it is improperly engineered. The harness and more importantly, the wiring, should not be compromised. Sometimes pins are in a position to receive heat, radiated from an external source, but it being at the module-end of the harness, should make that less of a factor. But automakers don't seem to be shy about keeping modules away from the engine like they used to. If this was an engineering failure, we should be seeing a lot of cases of this; particularly with the hotter states and in the next several years.

 

[PhoenixM3]

Update. The fan does function, but I believe it’s drawing more current than the controller can supply OR the controller is indeed bad. A couple days ago, I tried to get the fan running with a 12VDC power supply, but didn’t have a good connection (charred positive terminal).

‘’If someone has interest/opportunity to measure the VDC on the fan side of the controller, I be grateful. I measured 14.35 with AC off and 14.45 with it on and the car was NOT up to operating temperature.

 

[Ford ST]

Well the voltage would not be any higher than that. What would need to be measured is the amperage that is being pulled.

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[PhoenixM3]

Well the voltage would not be any higher than that. What would need to be measured is the amperage that is being pulled.

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Guess you’re right, but was looking for comparison of fan module’s output from someone who has a working system. I don’t think the module is sold separately anyway....

 

[Ford ST]

Guess you’re right, but was looking for comparison of fan module’s output from someone who has a working system. I don’t think the module is sold separately anyway....

I don't believe it is either. The voltage cannot exceed what is at the battery. The only proper way to diagnose the fan module is with a scan tool that can control the output.

View: https://youtu.be/u0-kgf9fjeg


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[PhoenixM3]

I don't believe it is either. The voltage cannot exceed what is at the battery. The only proper way to diagnose the fan module is with a scan tool that can control the output.

View: https://youtu.be/u0-kgf9fjeg


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Anyone know if the module is sold separately?

 

[Intuit]

That module won't be cheap. Look for a wrecked donor. For example: https://upullandpay.com/ Got a photo of the burnt pin on the module? The module will have a part number on it, that can be looked up online. Dealer parts center can look up the part and price.

If the pin ain't burnt, use it. Unless there's a weak connection to ground, power regulation is typically pretty reliable. Regulation typically fails before over-current or over-volt.

Direct testing of a fan motor unfortunately requires disassembly:
https://www.bing.com/videos/search?...8393D2F9E0436A53EE368393D2F9E043&&FORM=VRDGAR

Replace or bypass any any burnt pins, wiring. If the fan bearings are rough or noisy, or the fan is off-balance, which can sometimes be hard to detect until it's spun-up to full speed, replace the fan. If the fan seems stiff, replace it.
If you can see any part of the fan motor, look for signs of scorching.

Haven't looked at the video posed for the module above, it may well include a test for the fan; or even rely on the fan for testing results.

 

[M-Sport fan]

I fully plan on replacing the WHOLE fan assembly when I install a Mountune radiator, as my factory shroud/housing has warped soooo badly it is almost an inch away from the factory radiator's surface in some spots.

I do wish that there was an aftermarket, more powerful/higher CFM, and NON-warping option for us. (YES, I know that the Mishi shroud is metal/alloy, but it still uses our factory fan, correct??)