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Chris (aka- Moose)
Chris (aka- Moose), Technician
Category: Lincoln
Satisfied Customers: 2046
Experience:  16 years experience with Lincoln
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Our 2008 Lincoln MKZ keeps overheating at idle. I have

Customer Question

Our 2008 Lincoln MKZ keeps overheating at idle. I have replaced the cooling fan and thermostat and still it happens.
JA: Sometimes things that you think will be really complicated end up being easy to fix with a Lincoln. The Lincoln Mechanic I'm going to connect you with knows all the tricks and shortcuts. Tell me a bit more about what's going on so he can help you best.
Customer: The car intermittently overheats after sitting idle for a good while, in heavy traffic, parking lots, etc., with the AC on. I have replaced the radiator cooling fan unit and the thermostat, but it continues to happen.
JA: Are you hoping to fix this yourself?
Customer: I'd love to. I've done everything myself so far
JA: Is there anything else important you think the Lincoln Mechanic should know about your Lincoln?
Customer: Nope
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Lincoln Mechanic about your situation and then connect you two.
Submitted: 9 months ago.
Category: Lincoln
Expert:  SARMIENTO22556 replied 9 months ago.

Hello, I will try to help you with your concern.

When you say you replaced the cooling fan unit, what exactly did you replace?

Are the fans not even coming on with the a/c on?

Customer: replied 9 months ago.
The radiator fans in this car are electric and come as one complete unit that sits immediately behind the radiator. A local repair shop diagnosed the overheating issue as the radiator fans malfunctioning, so I replaced it myself. The fans will come on when the engine is warmed up.
Expert:  SARMIENTO22556 replied 9 months ago.

thanks for the information. I do know that they are electric. did the new fans come with a fan control module as well?

do the fans come on at idle when warm and still overheats? overheats with the fans running?

Customer: replied 9 months ago.
Unfornately, I've never seen it happen as this is my wife's car, and haven't been able to replicate the failure, as it is intermittent, so I don't know if the fans are running when it overheats. From what I've read, the fans are controlled by the PCM and do not have a separate controller. No controller came with the fan unit. It was one electrical connection to complete the installation.
Expert:  SARMIENTO22556 replied 9 months ago.

let me look at the wiring schematic. I will get back to you shortly

Expert:  SARMIENTO22556 replied 9 months ago.

after looking at the schematic, yes the fans are controlled by the pcm.

It is going to make this harder if you can't recreate the issue.

There are several possibilities that could be occurring :

The pcm might be at the fault

the pcm is not receiving the proper signals needed to turn on the fans

bad sensor(s) or wiring

Customer: replied 9 months ago.
I have finally replicated the problem. Sitting at idle the fan will come on for a second or two every 20 seconds or so on a low setting, keeping the temp in the normal range. At some point it stops coming on at all and the temp goes high and eventually overheats completely (I didn't let it go all the way) with the fan not running.
Expert:  SARMIENTO22556 replied 9 months ago.

ok so the pcm is not seeing the signal it needs to turn on the fan to a higher speed or at all.

are there any stored engine codes in the vehicle?

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