Weird 2019 Max AC Issue

[BlakeMAX2019]

Our 2019 MAX AC is acting funny, and I’m curious if anyone has run into something similar.

About an hour into a road trip, with the AC on and the fan set to high, the fan will suddenly drop to what feels like the low setting—even though it’s still set on high. At the same time, the air coming out isn’t as cold as it normally should be. Basically, the airflow is very weak even though the fan control is on high.

Here’s the odd part:

• If I turn the AC button off but leave the fan set to high, the fan immediately ramps back up and blows strong again.
• I kept it like this for about 10 minutes (fan on high, AC off), then pressed the AC button back on—and the air got cold again with the fan blowing hard as it should.
• This has happened a couple of times before, but this was the first time I experimented with turning the AC button off to test it.

Anyone have thoughts on what could cause this?

 

[99WhiteC5Coupe]

Our 2019 MAX AC is acting funny, and I’m curious if anyone has run into something similar.

About an hour into a road trip, with the AC on and the fan set to high, the fan will suddenly drop to what feels like the low setting—even though it’s still set on high. At the same time, the air coming out isn’t as cold as it normally should be. Basically, the airflow is very weak even though the fan control is on high.

Here’s the odd part:

• If I turn the AC button off but leave the fan set to high, the fan immediately ramps back up and blows strong again.
• I kept it like this for about 10 minutes (fan on high, AC off), then pressed the AC button back on—and the air got cold again with the fan blowing hard as it should.
• This has happened a couple of times before, but this was the first time I experimented with turning the AC button off to test it.

Anyone have thoughts on what could cause this?

Ford issued a TSB (not a recall) on how to repair this issue. It involved replacing the a/c evaporator due to a defective temperature sensor which is part of it. The evaporator freezes and airflow is reduced, until it is parked and thaws out.

I previously posted a link to the TSB (via the NHTSA website) on another post, but do not have a link to it now.

EDIT: https://static.nhtsa.gov/odi/tsbs/2022/MC-10206843-0001.pdf

 

[BlakeMAX2019]

I’ve seen that one. On the way home, about 2hrs of continuous proper operation. That TSB I’m sure is a pricey repair. They have to take the dash out from what I understand.

 

[2019XLT]

I have the same issue and just got used to switching AC off fan runs high and seems to thaw it out then runs fine. In my observation the freeze up typically occurs when starting vehicle on a hot and more humid day, not after it’s been running a while. So after that initial dethaw following starting AC on a hot day it doesn’t freeze up again for me. I also make sure to recirculate air to keep that dryer inside air going through the system.

And yes the fix involves tearing up the dash and that’s just too much cost, but I’m at 120,000 miles and await my transmission to blow up and day so I’m not willing to put much into any fixes on this vehicle at this point lol…

 

[65Rustang]

We just had the same problem. Except when I turned on the rear AC on high it would thaw out for awhile. We were on a 9 hour trip, so I ended up turning the ac button on downhill, and leaving it off uphill.
It kept the car cool for the trip.
On household ac's when they freeze over they are usually low on Freon. Or the filter or fan isn't allowing air flow.
So I added a can of the new 1234YF refrigerant... It needed it, and it fixed the problem.