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2008 SE, 2014 SE
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9 Posts
Discussion Starter #1
Hi all,
I bought my daughter this car a little under a year ago and it has not been one of my better purchases. Within a couple of months of getting it, she was sitting in traffic and got a warning message telling her the car was overheating and to pull over and shut down as soon as possible. She brought it home, I noticed that the coolant was low and topped it up. We went for a number of months without an issue (not really surprising, since it was winter). About 6 weeks ago, it happened again and again the coolant level was low. I had read in earlier posts that sometimes the reservoir cracks and it looked like that might be the case, so I replaced it. A week or so later, she got the pull over message again. She brought it home and I inspected the underside, noticing some leaking from the radiator. I decided to replace it and did the hoses at the same time, along with the thermostat. I also suspected the fan controller was bad, as the fan was not coming on when the AC turned on. I replaced it with a used OEM part and it seemed to be working fine. I also pulled the fan relay and bench tested it--no issues there. Then tonight, she was waiting in line in a drive through for about 20 minutes and the car overheated again, this time the steam coming out from under the hood was obvious. I came down, checked all the hoses--tight, no leaks, filled the reservoir and drove home with no issues (72 degrees outside and not very much idling). I suspected the fan was not coming on, as that would explain overheating in the drive through line and the AC. Sure enough, when I pulled into the driveway and turned on the AC, no fan. I am wondering what to do next, as I've checked the relay, replaced the controller and the whole rest of the system is basically new. The fan seems to work intermittently, so this has me really confused. I've also hooked up my OBD II reader and there are no codes. I'm suspecting the PCM, as the fan seems to not be getting a 'turn on' signal for either the AC or the coolant temp at a certain point, and it seems this is after the car has been running for a while and then is either stuck in traffic or a long drive through line like tonight. Has anyone seen this and have any suggestions? I've also recently had the transmission totally rebuilt due to the issues with that notorious piece of equipment, so this is the last thing I needed...thanks in advance for any help.
 

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2004 Focus Wagon, Zetec DOHC, Auto
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...pulled the fan relay and bench tested it--no issues there.
Bench testing relay is not always reliable. A failing relay can work (make contact) and then then not work. I have seen many relays work intermittently while on their last legs. Cheap enough to replace and eliminate as a possible cause.
 

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2008 SE, 2014 SE
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9 Posts
Discussion Starter #4 (Edited)
Pull the wiring connector to the cylinder head temperature sensor. If the fans come on the sensor is bad.
Ok, just tried this. Disconnected the wiring connector from the sensor, started the engine and the fan came on immediately. So, that confirms a bad sensor, but what about the AC? Sometimes it will not come on when the AC is turned on. Either way, it seems this eliminates the relay as an issue? Picking up the new sensor from O'Reilly's today and will install that.
 

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2008 SE, 2014 SE
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Discussion Starter #5
Also, any idea about how much coolant I need to drain to get below the sensor? I'm hoping to avoid removing the air deflector and lower engine covers if I can. I have a pump that can empty the reservoir, but that's about it.
 

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2006 ZX3 2.0, 2006 ZX5 2.0, 2004 ZX3 SVT
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I hate to tell you anything after reading about this issue.for an hour on other sites.Dont want you throwing parts at it. Could be the module, relay or the cht. If you do decide to replace it the engine needs to be cold. The sensor has no coolant going to it. It infers coolant temperature from the cylinder head metal temperature. It does not measure the liquid temperature.
 

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2008 SE, 2014 SE
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Discussion Starter #7
I pulled the old sensor (on this model, it is in contact with the coolant) after draining about a quart...not too bad. But as you can see from the photo, the o-ring is pretty gnarly, so probably good to change regardless:
20200523_115931.jpg
 

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2008 SE, 2014 SE
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Discussion Starter #8
Well, I installed the new sensor, and ran the car in the driveway for an extended period of time, waiting for the fan to kick on. It never did, and eventually the high temp--shutdown engine warning came back on. Right after this occurred, I turned off the engine, swapped the rear window defrost relay with the fan relay and started the car again--still no fan. At this point, I have to conclude that it's likely in the PCM, but in any case is probably beyond my ability to diagnose, unless I want to buy one of those fancy tools. No OBD II codes being thrown...very frustrating. I think I'm going to try my local shop, who are pretty honest and reliable, and see what they come up with.

My only last ditch idea was to try and reset the PCM. Found this YouTube video that shows how:

Not sure it will do anything, but don't think it can make things any worse...
 

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2004 Focus Wagon, Zetec DOHC, Auto
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Have you tried running the cabin heater at full blast. If the heater does not continue putting out hot air as normal, then water pump is not working correctly.
 

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Discussion Starter #10
Have you tried running the cabin heater at full blast. If the heater does not continue putting out hot air as normal, then water pump is not working correctly.
Thanks, will give that a try tomorrow
 

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Discussion Starter #11
So, I tried resetting the PCM today, using a jumper across the positive and negative battery cables (removed from the battery of course); no change. No fan for A/C on, and none while idling (86 degrees today, so good day for this test). Car got all the way up to the "overheating-shut down engine" warning again. I think this one has exceeded my technical limits, so will be taking to the shop next week.
 

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So, I tried resetting the PCM today, using a jumper across the positive and negative battery cables (removed from the battery of course); no change. No fan for A/C on, and none while idling (86 degrees today, so good day for this test). Car got all the way up to the "overheating-shut down engine" warning again. I think this one has exceeded my technical limits, so will be taking to the shop next week.
It's been a while since I've been under the hood of a 2014 Focus. We don't get many where I work now so I have to ask this..... Look on the fan shroud. Is there a small module attached to it?
 

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2008 SE, 2014 SE
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Discussion Starter #13
It's been a while since I've been under the hood of a 2014 Focus. We don't get many where I work now so I have to ask this..... Look on the fan shroud. Is there a small module attached to it?
Yep, it has a module. I replaced it last week with used OEM one that the Seller confirmed worked. It behaves the same as the old module did, which would either be a huge coincidence, or eliminates the module as the issue. I wish I had the diagnostic equipment to test it, though...
 

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Either the module is bad, a relay is bad, a fuse is bad, wiring is bad, or the fan itself is bad.... Or we can go with the typical answer to every problem on this forum and blame the O2 sensor....
 

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Discussion Starter #15
I can get the fan to turn on, so I know the fan motor is ok. Also, I have both bench tested the relay and swapped it with other relays that are identical in the fuse box. What fuse would be in this system? From what I can see in the Haynes wiring diagram, there is not a fuse, and the owner's manual does not indicate one either, but I could definitely be missing something. Lol on the O2 sensor...
 

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I can get the fan to turn on, so I know the fan motor is ok. Also, I have both bench tested the relay and swapped it with other relays that are identical in the fuse box. What fuse would be in this system? From what I can see in the Haynes wiring diagram, there is not a fuse, and the owner's manual does not indicate one either, but I could definitely be missing something. Lol on the O2 sensor...
How exactly are you testing the fan? If you're connecting it directly to a 12V source, you're only testing high speed operation. You can't properly test low speed operation without a scan tool. Forscan might be able to do it, but you'll need an OBDLink MX.

Personally, I'm not a fan of Haynes manuals. I've run across too many instances where the information was just flat out wrong and resulted in unnecessary part replacements.

Stick around, you'll understand the comment about blaming the O2 sensor.....
 
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