[ralawren]

Has anyone experienced the AC reducing its cooling after cruising at high speeds ( 85mph plus?) I just drove 3 hours to the beach and during a one hour extended cruise at 85+ mph the AC all but stopped working. The outside temperature was 90+. Engine RPM was only 2600 in my 228i.

I finally turned it off. About 20 minutes later I turned it back on when cruising at 70 mph and everything was back to normal.

Is there a sensor that adjusts the AC if the engine begins to run hot?

Not sure if I need to go see the dealer before my warranty expires in July or not.

Appreciate any advice / similar experiences.

[TajoMan]

Most likely the freeze probe on the evaporator is not working properly and leads to freeze the evaporator.
If your warranty expires in July, visit dealer now.

[Sportstick]

Originally Posted by ralawren

Has anyone experienced the AC reducing its cooling after cruising at high speeds ( 85mph plus?) I just drove 3 hours to the beach and during a one hour extended cruise at 85+ mph the AC all but stopped working. The outside temperature was 90+. Engine RPM was only 2600 in my 228i.

I finally turned it off. About 20 minutes later I turned it back on when cruising at 70 mph and everything was back to normal.

Is there a sensor that adjusts the AC if the engine begins to run hot?

Not sure if I need to go see the dealer before my warranty expires in July or not.

Appreciate any advice / similar experiences.

Arm chair guesses here, but don't think it is related to speed. More likely related to distance/time. A system which has lost some of its charge may freeze up over time and lose its ability to cool the air, forming an actual chunk/block of ice. This sounds like a service visit and my guess includes that they will find a leak of refrigerant. Meanwhile, I suggest not using the system.

[p912guy]

As others have said, not normal. Time for a service visit.

[hwntime]

Were you in ECO mode? I noticed when on long drives on the freeway in ECO, the AC does have a significant drop in cold air output when at low RPM's.

[BEM-S4]

I was told that under aggressive driving the AC will retard itself as needed so as not to impact performance - per one of the instructors at SC performance center.

[delvec03]

Originally Posted by TajoMan

Most likely the freeze probe on the evaporator is not working properly and leads to freeze the evaporator.
If your warranty expires in July, visit dealer now.

second this. May or not be the probe?

mine, and others have had could freeze over which still makes cool are but very low flow coming out of the vents. the F30s had this issue too.

[ralawren]

Freezing over after extended cruising sound like the culprit. The air still ran but the cooling degraded substantially. Called dealer on 5/31 and first appointment is 6/11.

Thanks for all the advice! Will provide an update once I hear from my SA.

[DaleHeinz]

I've had a few issues with my a/c. First was a bad compressor/coolant pump issue, and 40,000 miles later it was a radiator issue. Both replaced under warranty. Took them 4 days to diagnose the first issue. It was over pressurizing, which caused the system to shut down.

[AndDown]

Originally Posted by DaleHeinz

I've had a few issues with my a/c. First was a bad compressor/coolant pump issue, and 40,000 miles later it was a radiator issue. Both replaced under warranty. Took them 4 days to diagnose the first issue. It was over pressurizing, which caused the system to shut down.

I had a drivetrain malfunction alert in our 428i that turned out to be a result of high pressure in the A/C line, compressor not shutting off. There was subsequently a slight whining groaning sound audible when starting up in 1st gear. They traced the sound to the compressor which was replaced under warranty. Seems like this is becoming a common issue with the compressor.

[DaleHeinz]

Originally Posted by AndDown

I had a drivetrain malfunction alert that turned out to be a result of high pressure in the A/C line, compressor not shutting off. There was subsequently a slight whining groaning sound audible when starting up in 1st gear. They traced the sound to the compressor which was replaced under warranty. Seems like this might becoming a common issue with the compressor.

That's pretty much what mine did the first time. I could actually feel the compressor or pump kicking on and off and hear it, when stopped at a red light. Almost like a wurring sound and then a slight clunk when it kicked off that I could feel.

[smbm5]

Ralawren, what was the diagnosis of your a/c issue? Just drove 400 miles in the Florida heat with the last 175 miles without a/c. Appreciate your response.

[TajoMan]

Originally Posted by DaleHeinz

That's pretty much what mine did the first time. I could actually feel the compressor or pump kicking on and off and hear it, when stopped at a red light. Almost like a wurring sound and then a slight clunk when it kicked off that I could feel.

In case of 428 vs 240, cause of AC high pressure can be totally different.
M240 has water cooled condenser and 428 has traditional air cooled condenser.

In case of M240, there was some cases with electric coolant pump issue in secondary coolant circuit or punctured secondary radiator. In those case, AC would has high discharge pressure.

For 428, it is likely the AC pressure sensor issue or compressor itself problem.

[AndDown]

Originally Posted by TajoMan

In case of 428 vs 240, cause of AC high pressure can be totally different.
M240 has water cooled condenser and 428 has traditional air cooled condenser.

In case of M240, there was some cases with electric coolant pump issue in secondary coolant circuit or punctured secondary radiator. In those case, AC would has high discharge pressure.

For 428, it is likely the AC pressure sensor issue or compressor itself problem.

You’re correct re the AC pressure sensor was faulty in our 428i resulting in high pressure in the line.

[makrop]

Just had the same thing happen to me. Cruise at 80mph. Air temp here in Oklahoma was 90+. AC pretty much stopped blowing about an hour in. Had it on max AC and could hardly feel any air. Gave up and turned it off and opened window. Car only has 8,000 miles...

[ralawren]

Originally Posted by smbm5

Ralawren, what was the diagnosis of your a/c issue? Just drove 400 miles in the Florida heat with the last 175 miles without a/c. Appreciate your response.

My appt is 7/10 so will post the results next week.

Thanks for all the feedback. It sounds like there probably will be an issue that needs to be resolved in the 48th month of ownership😀.

[19bis]

Originally Posted by makrop

Just had the same thing happen to me. Cruise at 80mph. Air temp here in Oklahoma was 90+. AC pretty much stopped blowing about an hour in. Had it on max AC and could hardly feel any air. Gave up and turned it off and opened window. Car only has 8,000 miles...

I recently experienced this in my F31, but haven't seen this in my F22 (yet). There is a TSB for the F30s at least, 64-06-13.

There are a few things that may help reduce the likelihood of this happening:

-- turn up the intensity (fan speed) in auto mode (before the system ices up - once the air flow cuts off, you have to turn off the AC for a while to let it thaw out).

-- switch recirculation to manual - recirculated air is less humid, so does not cause as much icing.

-- drive in eco-mode (though who wants to do that?).

[ralawren]

Originally Posted by 19bis

I recently experienced this in my F31, but haven't seen this in my F22 (yet). There is a TSB for the F30s at least, 64-06-13.

There are a few things that may help reduce the likelihood of this happening:

-- turn up the intensity (fan speed) in auto mode (before the system ices up - once the air flow cuts off, you have to turn off the AC for a while to let it thaw out).

-- switch recirculation to manual - recirculated air is less humid, so does not cause as much icing.

-- drive in eco-mode (though who wants to do that?).

The dealer tech found a service bulletin - SIB 64 03 16 Intermittent reduction in airflow

Solution was update the software that controls the cold air flow. Apparently it allows the cold air to run too long and causes the unit to freeze. Just like you all reported. Now the new SW will prevent cold air unit from running so long that it freezes. Sounds logical but will not know until my next 2 hr plus trip in the heat.

[JMartz]

rlawren

It seems improbable that a software correction would resolve the evap-freeze issue. My car has 45,000 miles. I have driven it at freeway speeds in hot weather repeatedly w/o an a/c malfunction. Suddenly on the 4th of July, during a 50 mile drive, the evap froze and all air flow and cooling ceased. It just does not seem plausible that a software misprogramming would suddenly begin to cause a cooling problem. What about the 3 years and 40,000 miles plus with no problems?

[TajoMan]

Originally Posted by JMartz

rlawren

It seems improbable that a software correction would resolve the evap-freeze issue. My car has 45,000 miles. I have driven it at freeway speeds in hot weather repeatedly w/o an a/c malfunction. Suddenly on the 4th of July, during a 50 mile drive, the evap froze and all air flow and cooling ceased. It just does not seem plausible that a software misprogramming would suddenly begin to cause a cooling problem. What about the 3 years and 40,000 miles plus with no problems?

It is very easy to do it with software.

AC control has a setting to 'reduce or turn off' the AC compressor.
It's typically few degrees above freezing temperature (depends on manufacturer).

They can simply just raise that setting couple of degrees to prevent the freezing. (downside is that you may lose AC performance a little)

[Richard Welch]

I am taking my ‘18 M240i in for this issue this week. I will post the results of this service visit.

[XutvJet]

Are those that are experiencing this issue running the AC at max cooling?