A/C went from low to full blast by itself

[JessicaD]

I have a 2017 Explorer Sport. I was in traffic yesterday and in a 5 minute period my back A/C unit would turn up to highest fan setting and coldest temp setting by itself. It happen when I was coming to a stop each time. I'm not sure what to think, and ideas of the issue?

 

[teastone31]

Mine does that too, not just when I stop. It randomly does it. It’s 47 leaving work and raining. I have the defrost on or running the heater, Auto off, and all a sudden the ac blows max and lo setting. It seems to get stuck when trying to turn it off. About 2 or 3 months ago in the summer it would do it too when the ac is on. I don’t like it on max. Too loud. But something has got to be wrong with the thermostat or something. Why?? How can I fix this?

 

[peterk9]

Mine does that too, not just when I stop. It randomly does it. It’s 47 leaving work and raining. I have the defrost on or running the heater and all a sudden the ac blows max and lo setting. Why?? How can I fix this. It started doing that a few months ago.

Welcome to the Forum.
When you are using Defrost, the A/C automatically turns on to dehumidify the interior. As to why it periodically goes on full blast is the issue here.
It could be a failing control module. You may have to take it in to have it checked out/diagnosed.

Peter

 

[peterk9]

Mine does that too, not just when I stop. It randomly does it. It’s 47 leaving work and raining. I have the defrost on or running the heater, Auto off, and all a sudden the ac blows max and lo setting. It seems to get stuck when trying to turn it off. About 2 or 3 months ago in the summer it would do it too when the ac is on. I don’t like it on max. Too loud. But something has got to be wrong with the thermostat or something. Why?? How can I fix this?

Welcome to the Forum.
When you are using Defrost, the A/C automatically turns on to dehumidify the interior. As to why it periodically goes on full blast is the issue here.
It could be a failing control module. You may have to take it in to have it checked out/diagnosed.

Peter

 

[teastone31]

Welcome to the Forum.
When you are using Defrost, the A/C automatically turns on to dehumidify the interior. As to why it periodically goes on full blast is the issue here.
It could be a failing control module. You may have to take it in to have it checked out/diagnosed.

Peter

Thank you

 

[gatzdon]

With an OBDII reader and Forscan, you can monitor the individual button presses on the FCIM to see if you are getting "ghost" presses, which would explain the behavior that you are describing.

If that's the case, some have reported success with removing the FCIM and cleaning it. If you are unlucky like me, the capacitance sensors are degraded and you have to replace the FCIM. Ford no longer carries it.