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AC Air Flow Lessens After Some Time

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2016 MS A/C Question. When I first get in the car it blows just fine. After the system is on for a long time (2 hours?) it is still blowing cold air but it is barely coming out of the vents. The front louvres (at the bottom of the front bumper) are open so I know it isn't getting blocked there. New cabin filter. What could be the culprit to stop the flow of air after a long period of time? I know in Home AC systems, if you have low refrigerant it can sometimes freeze up the coils because it is working too hard and that causes the air flow to drop. Could that be happening here too?
 
I have heard of the condenser in the cabin freezing up in high-humidity climates. If after it stops working, you stop for 15 minutes with AC off, and it starts working after that, that could be the cause. It's probably not low refrigerant.

In this era of cars, battery cooling can also take priority, so that on a hot day on a demanding power (i.e. high speed), the car may shift cooling to the battery over the cabin. This might be more noticeable going up a long hill. The newer LR/Plaid has far more thermal cooling power and seems to have eliminated the issue.
 
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I recently started experiencing similar A/C issues. Maybe within the last 2 months. I have an appointment scheduled for later this month so maybe ill get additional info to share with the forum.

Purely speculation but I’m thinking there is a problem with a sensor or a computer issue. I cant tie it directly to a particular sofare update but i know its a new problem. I have solve the issue by powering the car off and letting it sit for a couple minutes before doing anything. A/C works just fine afterwards. Sroll wheel reset alone did not solve the problem.

2017 MS 75D 2022.20.8 MCU2
 
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I have the exact same issue, all four seasons. Starts out fine, then after an hour or two, very low air flow. Been to service 3 times - no trouble found. It is annoying on long trips. There is another similar thread with no resolution: Weak air flow. Happened on MCU1 and now on MCU2.

Best I have found when it happens is to set ventilation is to manual, crank up the fan speed, select the dash vents and play with the temp to get comfortable. Stop for a charge, get back in the car, it is good for another 2 hours or so.
 
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