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Overheating question

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New User

Mar 21, 2021, 9:37 PM

Post #1 of 3 (558 views)
Overheating question Sign In

Hello everyone, I appreciate any advice as I cant get my car looked at until the morning and I would appreciate as much feedback and 2nd opinions anyway, but this will hopefully ease my mind for now.

So the car is a 2012 ford fusion SEL. My girlfriend delivers newspapers so shes driving for a few hours per night. The last 2 nights, she has noticed if she switches the heat on, the temperature will rise up to hot. Turning it off makes it go back down. Turning the car off, sometimes there is a slightly louder fan sound that lasts 5 or 6 seconds after being shut off that gradually over those few seconds gets lower and lower until it stops. No issues with overheating while driving without the heat, and it's even fine if we just turn the floorboard heating on. No smoke, engine doesnt seem unnecessarily hot when I pop hood, coolant tank isnt bubbling or abnormally hot. Always trying to learn new things about cars so I can eventually do more and more things myself, so I am interested in the mechanics behind this and why it's doing what it is, as much as I am looking for the solution.

Thanks in advance, hopefully someone helps me out so I can at least rid the suspense tonight while she is out

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Mar 21, 2021, 11:02 PM

Post #2 of 3 (546 views)
Re: Overheating question Sign In

This is a bit too much "second hand" info on what happens when as SHE says "this" and you come here to ask about it.

No prob just adds to difficulty to pin down something. Fan(s) must work for radiator many are forced to work when not on just plain heat but will if another request like defog/defrost or a choice of something A/C.

So what to do? Running heater full blast even if it's not wanted usually would help? That leaves fan(s) for radiator to me so far?

It works but may not know when to on time or just might be normal for the car you said YOU didn't observe boiling which is too late.

System must hold pressure and be full. Problem now with my response is heater apparently works so suggests it's actually full of coolant but not for sure.

It may have a lurking exhaust leak into cooling system, the dreaded needs a head gasket job is not so easy so far.

You if time could start it cold and feel for or measure pressure from warming up normally with testers for pressure too early but need to know what too early would be I can't write that much!

See if it will cool down if car's gauge is into real hot area with water sprayed/misted at it thru grille. Some info to help might come if that totally fixes it.

This is best left to in person observations by a qualified tech IMO as it may be normal for this car IDK and playing second fiddle to the driver of it isn't helping - no offense, glad you are trying to help her,


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Mar 22, 2021, 4:53 AM

Post #3 of 3 (534 views)
Re: Overheating question Sign In

At this point you have no info at all. Let the mechanic look at it and find out what kind of issue it has.

It could have a small leak somewhere that gradually created an air pocket in the cooling system or it could be something entirely different. Let them check it out first.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

(This post was edited by Hammer Time on Mar 22, 2021, 4:54 AM)

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