Cooling Fans stay on when A/C switch is pressed

[jasonn5.0]

Hi guys I have a Mustang GT 2017, worrying about my car overheating.

I noticed a while ago my cooling fans only kick on when I press my A/C button.
Note: A/C does not blow cold air unless it's cold outside (obv), I don't NEED A/C as I live in Ireland and we only get a week of summer however I'm considering getting freon topped up to start to diagnose this issue.

Cyld Head Temps(celsius) on avg are 92 -94 but when underload or idling in traffic I notice it start to creep up to 102/104 which is usually when I press the a/c button to turn on the cooling fans. (usually I catch this before it even reaches 98 degress bc Im constantly monitoring)
When I press the a/c button the cooling fans kick on full blast and stay on regardless of if a/c is turned off after or not.

I can hear the a/c clutch engage and hear the a/c try to push out like a swoosh sound (normal a/c noises ) gives cold air for a few seconds then blows normal air.

Which way would you guys go to diagnose this issue?
I would bring it to ford but they would charge me countless hours as its not in warranty and they don't have huge experience on these cars in Ireland(I know they have an app that gives them instructions on how to do it but I'm not paying €60 an hour I usually bring it to a mechanic that works in there out of hours)

Got him to check some fuses/relays related to the fans but all seemed normal enough

Getting a service done very soon so hoping to shed some light on this when I bring it to him.

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[Skye]

It's funny/strange the fans will not engage on their own, but will once the A/C button is pushed. And then stay on for a time after turning the button off. Like you need to jump-start the fans. While that activity is weird, it does show the physical and electrical connections from the Powertrain Control Module (PCM) to the fans are OK. That the fans are OK.

So the fans will come on when the button is pressed, as they should. But won't come on by themselves. And the temp gauge is giving you a reading, so the Cylinder Head Temp (CHT) sensor is working.

I cannot offer ideas as to how to get the fans to work on their own. But as they are related to the A/C system and we know it has problems, I feel the A/C needs to be fixed first. Remove that faulty area and get it working right, then see how the fans act.

I also lean to the A/C from a cost perspective. While you can at least get the fans working, the inoperable A/C could be due to a leak. If there is a leak, the longer the internals of the A/C system are exposed to outside elements, the greater the risk of internal rot and damage. And maybe along the way, the fans will begin working correctly or the tech will see tells leading them to that problem.

I'm attaching a pic of temps (in F) when the fans would normally come on.

ádh mór

 

[ORRadtech]

Don't just "top off" the refrigerant. Have it evacuated and put into a vacuum to test for a leak. It does sound like you have a leak and the first generation of S550 were prone to evaporator leaks, something the dash has to come out to repair.
Still, that should not prevent the fans from coming on. You gave head temps but not coolant temps. I would expect cooling fan operation to be linked to coolant temps not cylinder head temps.

 

[jasonn5.0]

Thanks @Skye & @ORRadtech for the info

I'll definitely start from the A/C.
Have it repaired/fixed and go from there.

The issue arrised when A/C stopped blowing cool air so it hopefully fixing that can fix the a/c.

Legend for sending on the chart at least I can know when to expect the fans to kick on if its working normally.

@ORRadtech I'm only going based off of what I can see on my dashboard. I know the Coolant temperature is the needle on the bottom left which never moves further than the half mark even if the Cylinder Head Temp is higher than usual.

I read another forum about Coolant Temp vs Cylinder Head Temp which would mean that the most accurate way to read temperature whilst driving or sitting in traffic if I'm not wrong. However they did say that there is a Radiator Coolant temp which I'm guessing could be read through plugging in obd?


Thanks again all for the help
Getting somewhere now at least

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