AC turns cold even after replacing door actuator & temp sensor

[Musty-S550 GT]

Hello fellow forum members,

Recently I bought my first mustang, a 2017 Base PP GT from the USA.

From the moment I got it there was an issue with the AC and it still is not fixed. I have a base model so it is the Manual AC.

The symptoms are:

The first 5-20 minutes the AC works fine and the heater works in combination with the AC so I have warm air and the AC makes the air dry.
After 5-20 minutes there comes cold air out of the vents and I cannot control the temperature anymore with the controls.
I also see that the door actuator on the drivers side is turned to the cold position and it doesnt move anymore. So I assume that somewhere there the problem must be.
When I turn off the FCIM and turn it on again the AC in combination with the heater is working fine again for about 5-20 minutes and then it turns cold again..

The strange thing is that when I turn the heater on WITHOUT the AC it stays working fine all the time with warm air, but when I turn off the AC when it is stuck in cold position it cannot heat the car anymore unless I turn the FCIM off and on again.

I already replaced the stuck door actuator for a new one and installed a new tempsensor but still I have the same result.
Based on my findings I suspect it to be an electrical issue somewhere in the controls.

Does anyone experienced the same as me and do they have a fix?

Is it possible that my FCIM is broken?


Help is much appreciated

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[ORRadtech]

Have you tried resetting the module?
I think the procedure is to simultaneously hold the radio power and seek up buttons until it starts to reboot.

 

[Musty-S550 GT]

Have you tried resetting the module?
I think the procedure is to simultaneously hold the radio power and seek up buttons until it starts to reboot.

I tried to reset it thru disconnecting the battery for 30minutes, but I dont know if that is the right procedure.

Do you mean the buttons that I have circled in red on the picture?

 

[ORRadtech]

Disconnecting the battery will clear DTCs but doesn't reset/reboot the FCIM/APIM. I believe those are the correct buttons. A YouTube or Google search should turn up a tutorial.
I have the larger screen in all my Fords and did have an APIM failure in my '12 Edge. It's a known problem that usually presents as a black screen. I don't have any experience with the smaller screen but it is my understanding that it can be reset/rebooted with that procedure.
Good luck.

 

[Musty-S550 GT]

Disconnecting the battery will clear DTCs but doesn't reset/reboot the FCIM/APIM. I believe those are the correct buttons. A YouTube or Google search should turn up a tutorial.
I have the larger screen in all my Fords and did have an APIM failure in my '12 Edge. It's a known problem that usually presents as a black screen. I don't have any experience with the smaller screen but it is my understanding that it can be reset/rebooted with that procedure.
Good luck.

Unfortunately that procedure did not work.

If I do a test procedure on the FCIM with Forscan the AC does it longer than expected, but eventually after 20-30 minutes turns cold again..
Is there a way to calibrate the actuators? I think that is the next thing to try?

 

[Musty-S550 GT]

Also I noticed that if the AC is stuck on cold and then I turn it to max heat on the frond windshield (defrost mode I guess?) the AC turns warm and the blend door actuator also turns too the warm position.... As soon as I push the button to activate the dashboard vents and the windshield off the actuator turns too a much colder position....
What can trigger this strange behaviour??

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