2018 GT Fan Turns on after car shut off.

[bstreet5.0]

My 2018 after being driven, even for a short time, will occasionally start to run the fan on high after the car is shut off. It's very cold this time of year here so I found this very strange. My 2015 never did this even after driving long distances in 100 degree heat.

Has anyone else had this issue with their 2018 or similar issue with earlier years?

- When the car starts the fan is off...so it does know the engine is cool.
- The compressor clutch is not engaged when settings do not call for it.
- The compressor appears to run constantly (see comp clutch spinning)when
called on. (perhaps the issue) I believe it should be cycling on and off as
pressure is needed.

And yes I know...take it in. Just discussing. thanks

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[gmupatriot]

Have not noticed this on my 2018 GT. Could be a bad thermostat?

 

[Cobra Jet]

Just curious -

Before you had parked the car, how was it being driven:

1) Normal or Sport mode?
2) Just getting home after jumping off highway or localized driving?
3) Were you in a lower gear and engine revs were up before parking?

 

[bstreet5.0]

Just curious -

Before you had parked the car, how was it being driven:

1) Normal or Sport mode?
2) Just getting home after jumping off highway or localized driving?
3) Were you in a lower gear and engine revs were up before parking?

I'm actually still kind of babying it, haven't even gone over 5k rpm.

Normal mode
Has occurred with highway, local, and mixed driving.
Prior to parking only driving @ 25 mph for about 1 mile on neighborhood roads.

It's an automatic, wasn't holding low gears etc. Very low RPM.

Outside temps 20-30f. Basically the same way I always drove my 2015, and it never did this.

The problem is it's not consistent. That's always a pain when trying to diagnose something. I keep the temp gauges displayed...nothing high or in the red.

 

[DickR]

My 2018 after being driven, even for a short time, will occasionally start to run the fan on high after the car is shut off. It's very cold this time of year here so I found this very strange. My 2015 never did this even after driving long distances in 100 degree heat.

Has anyone else had this issue with their 2018 or similar issue with earlier years?

- When the car starts the fan is off...so it does know the engine is cool.
- The compressor clutch is not engaged when settings do not call for it.
- The compressor appears to run constantly (see comp clutch spinning)when
called on. (perhaps the issue) I believe it should be cycling on and off as
pressure is needed.

And yes I know...take it in. Just discussing. thanks

I think this is a "functions as designed".

My 18 GTPP 10A does this frequently since day 1 in both cold weather and somewhat warmer weather. I mentioned this to the lead tech at the small dealer I bought the car from and he said that his 18 GT PP with manual does this also. Note that MANY cars have been doing this for decades but this is the first Mustang or other car I've had which does it. I've looked in the service manual but it isn't referenced that I can find in either the online manual or the online TSB's, etc.

Mine will run the fan once or twice that I've noticed in the cool weather we've had so far but I suspect more "cycles" in hot weather. It seems to be independent of "how driven" or "drive mode".

My assumption is that the primary, if not only, purpose is to cool underhood temps and fuel lines in order to reduce fuel evaporation emissions. The water pump is mechanical so any circulation from "hot water rises" would be minimal if the thermostat which is on the cold side of the system per the service manual stays open . . . I think.

 

[bstreet5.0]

I think this is a "functions as designed".

My 18 GTPP 10A does this frequently since day 1 in both cold weather and somewhat warmer weather. I mentioned this to the lead tech at the small dealer I bought the car from and he said that his 18 GT PP with manual does this also. Note that MANY cars have been doing this for decades but this is the first Mustang or other car I've had which does it. I've looked in the service manual but it isn't referenced that I can find in either the online manual or the online TSB's, etc.

Mine will run the fan once or twice that I've noticed in the cool weather we've had so far but I suspect more "cycles" in hot weather. It seems to be independent of "how driven" or "drive mode".

My assumption is that the primary, if not only, purpose is to cool underhood temps and fuel lines in order to reduce fuel evaporation emissions. The water pump is mechanical so any circulation from "hot water rises" would be minimal if the thermostat which is on the cold side of the system per the service manual stays open . . . I think.

This is what I was wondering if there had been some type of change causing this to happen? I was thinking if it was some failure of the thermostat or even just a sensor that it would occur all the time. I'l keep an eye on it, and maybe bring it up on my first oil change. When the weather starts to get warmer I'm curious to see if this will occur more often?

 

[nelson]

I have the exact same experience as you, driving the car nice, its cold here in CO, fan has turned on for 1-2 mins after parking and turning off the car twice now. Also have the 10 A/T, not sure why it does this but doesn't seem like anything is wrong otherwise.

 

[bstreet5.0]

I have the exact same experience as you, driving the car nice, its cold here in CO, fan has turned on for 1-2 mins after parking and turning off the car twice now. Also have the 10 A/T, not sure why it does this but doesn't seem like anything is wrong otherwise.

It's good to know others have the same experience. Certainly something to keep an eye on, but perhaps not an issue of great concern.

 

[MrTej]

+1 on this issue. It happened to me right after I drove it home from the dealer. Scared the crap outta me. I had a 2015 V6 before this one and I’m finding a few different “things” that never happened in the ‘15. I did call my dealer and my mechanic about this one, and both said that it is normal behavior.

 

[youra6]

Mine did this too.

 

[Semp1]

My 2018 after being driven, even for a short time, will occasionally start to run the fan on high after the car is shut off. It's very cold this time of year here so I found this very strange. My 2015 never did this even after driving long distances in 100 degree heat.

Has anyone else had this issue with their 2018 or similar issue with earlier years?

- When the car starts the fan is off...so it does know the engine is cool.
- The compressor clutch is not engaged when settings do not call for it.
- The compressor appears to run constantly (see comp clutch spinning)when
called on. (perhaps the issue) I believe it should be cycling on and off as
pressure is needed.

And yes I know...take it in. Just discussing. thanks

I know this post is old and This is normal. My issue is the fan stopped doing it after a Roush tune. Roush calibrator said they didn’t disable it in their power pak that ford installs btw. Now I’m bringing to ford to diagnose why it stopped. It’s a great feature that cools the engine faster so I want it fixed. Plus I will be switching to a custom tune after being fixed. Roush is too conservative.

 

[BlackandBlue]

I know this post is old and This is normal. My issue is the fan stopped doing it after a Roush tune. Roush calibrator said they didn’t disable it in their power pak that ford installs btw. Now I’m bringing to ford to diagnose why it stopped. It’s a great feature that cools the engine faster so I want it fixed. Plus I will be switching to a custom tune after being fixed. Roush is too conservative.

Open the drivers door after driving it hard to see if they kick on. I have noticed my fan will not be on or on low and if I open the drivers door the fan will kick on or kick into high gear.

 

[Semp1]

Open the drivers door after driving it hard to see if they kick on. I have noticed my fan will not be on or on low and if I open the drivers door the fan will kick on or kick into high gear.

That doesn’t correct the issue. It Hasn’t functioned since April/May. Something definitely occurred after ford installed the Roush power pack. They’re going to have to fix it. I’m going to have them reflash the stock tune any way to see if that corrects even though Roush claims they did not shut the feature off it since I’m going to custom tune. We shall see. I’m not really concerned to be honest the feature just should work because it’s a very good feature and was added for a reason.

 

[W.O.T. Stang]

It's nothing more than an after-run feature of the cooling fan/system. Most cars have been doing this for awhile. It's a nice feature to have.

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