Engine Fan Runs @ Max Speed Constantly

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Feb 17, 2016 | 12:38 PM

abarthuly

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Joined: Feb 2016

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Engine Fan Runs @ Max Speed Constantly

Hello,

I have noticed that my vehicles engine fan runs at max speed (and is very loud) all the time. Regardless of outside temperature, engine temperature, climate control settings, etc. It runs like that from the second I turn it on until I shut it off.

I have done some research online and found that people with a similar concern have been told that it could possibly be either the Coolant Temperature Sensor and/or Cylinder Head Temperature Sensor. I know that it could be a wide variety of issues, however it seemed as though these were common (and relatively easy) solutions. Does anything think either/both of these could be the problem? If so, please direct me to the proper part and instructions/video on how to install the new parts.

I would much rather spend ~$50 for two parts than screw around taking it in. If my attempts dont work, at least I know that I have 2 new parts in there. Or is this not really anything that I should worry about?
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Additionally, my climate control settings dont all work. And I have found through research that I need to replace the blower resistor. Would this have any impact on the engine fan?

Thank you in advance so much for your help.

I drive a 2012 Ford Escape XLT 3.0L V6

Feb 18, 2016 | 07:55 AM

tomw

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Joined: Jan 2002

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From: suburban atlanta

If you have manual HVAC control, the blower motor has a resistor pack that allows multiple speeds. It is located behind the glove box, attached the the incoming air plenum. I believe less than $20 at Ford dealer, or web site supporters.
The radiator fan(s) are controlled by the computer, with input from coolant or cylinder head temperature, road speed, and who knows what. The fan should be de-powered when traveling in excess of 30-something mph. Still works the same going over 48-ish kph.
I think there is one or more relays that operate the fan motors. A stuck relay could make the fan run whenever switched power is applied.
If you look in the power distribution box - PDB - under hood, read the legend, and find the relay that powers the fan. If there is a duplicate relay, note what it does, and you may be able to use it as a substitute to determine if the relay is not working properly.
If you have a scan tool, you can check the temp sensor used to determine fan operation for out of range values.
tom

Feb 18, 2016 | 02:56 PM

jbtecnico1

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Joined: Jul 2011

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From: PA

I had this same symptom in 2010.
Vehicle is 2005 Escape XLT 3.0 V6

Ford dealer diagnosed and replaced A/C Pressure Switch, was PN FMC 8C3Z 19D594 A, $25.98 for the part.

Good luck.

Feb 18, 2016 | 07:40 PM

abarthuly

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tomw:

Im assuming the Power Distribution Box is the technical name for the fuse box. So it could possibly be that I need to replace the relays in there that are connected to the engine fan?

What would you consider to be out of range temps?

If the temps are in range what do you recommend? If they are not in range what do you recommend? Other than the relays.

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jbtecnico1:

Thanks for that, are you referring to the engine fan problem? Would you think that it is still relevant considering mine is a 2012?

Also, do you have any pictures or videos to help me find that part in my engine?

Thanks guys, I really appreciate the help!

Feb 18, 2016 | 09:03 PM

ctubutis

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Joined: Nov 2007

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From: Denver Metro Area, CO

There was somebody here a few months ago who had this problem and he said his problem was caused by the relay. Instead of just throwing parts at it, you might do some actual diagnosis and see if you can't swap that relay with another adjacent one (assuming there are more than one available) and see if the problem moves with the relay's position (circuit) or not.

Feb 19, 2016 | 04:32 AM

jbtecnico1

Senior User

Joined: Jul 2011

Posts: 149

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From: PA

Yes, I'm not an AC guy but according to the Dealer, when the pressure builds in the system, the "switch" signals the fan to run. My opinion is that AC systems between '05 and '12 function similarly, thus this switch this is worth investigating. Bottom line, my problem was resolved. Btw, Dealer labor was $117 for this $25 part due to "research" required to understand the problem.

If you need to chase it down yourself, try www.ford-parts.com to find what you're looking for.

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jbtecnico1:

Thanks for that, are you referring to the engine fan problem? Would you think that it is still relevant considering mine is a 2012?

Also, do you have any pictures or videos to help me find that part in my engine?

Thanks guys, I really appreciate the help![/QUOTE]

Aug 4, 2018 | 01:27 PM

Daniel Benoit

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Joined: Aug 2018

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Engine fans on high speed continuously.

I had the exact problem as stated in the thread, 2012 F150 5.0L 133K in Maine with cool summers. The fix= faulty a.c. pressure transducer, easy fix $59 part. Easy install. The faulty part was giving false higher than normal pressure reading even with a.c. off, like over 720 psi. Not possible with a.c. off. So, faulty part.