Air conditioning in “auto” mode
Thread Starter
Senior Member
Joined: Feb 2025
Posts: 265
Likes: 89
From: Seattle
Currently ‘2015 S550 4matic. Previously 03 E320, ‘06 S430, ‘08 S550 4matic
Air conditioning in “auto” mode
Hi all…
I love this forum…
I’m still becoming familiar with my ‘15 550 4matic.
I got into the car after it had sat in the sun for a few hours today. The climate system was in the “auto” mode on both sides. Temp setting at 71 degrees on both sides.
After driving a few minutes, I noticed that the air coming out of the dash vents was not cold. Lowering the temp setting to 60 degrees did not result in colder air. My first thought was that the AC may need re-charging. Then I pushed the AC/Rest button and the AC activated and the air was immediately cold.
My question…Shouldn’t the AC come on in the “auto” setting when the car is hot inside? I thought that “auto” meant that the system would heat or cool “automatically” depending on the ambient temperature in the cabin. My previous ‘08 550 would blast AC cold air on start up in hot weather.
Any ideas about what’s going on?
Thanks
Chuck
I love this forum…
I’m still becoming familiar with my ‘15 550 4matic.
I got into the car after it had sat in the sun for a few hours today. The climate system was in the “auto” mode on both sides. Temp setting at 71 degrees on both sides.
After driving a few minutes, I noticed that the air coming out of the dash vents was not cold. Lowering the temp setting to 60 degrees did not result in colder air. My first thought was that the AC may need re-charging. Then I pushed the AC/Rest button and the AC activated and the air was immediately cold.
My question…Shouldn’t the AC come on in the “auto” setting when the car is hot inside? I thought that “auto” meant that the system would heat or cool “automatically” depending on the ambient temperature in the cabin. My previous ‘08 550 would blast AC cold air on start up in hot weather.
Any ideas about what’s going on?
Thanks
Chuck
Last edited by SSBN629 Seattle; Mar 25, 2025 at 08:24 PM.
Out Of Control!!
Joined: Nov 2018
Posts: 11,451
Likes: 5,352
From: San Francisco Bay Area
2019 C63CS
No, the AC compressor doesn't come on automatically if it's turned off. Auto essentially controls the air flow automatically, but doesn't automatically turn on the AC. Some people don't want the AC compressor on and would find it annoying if it overrode their preference. The only time the AC comes on automatically is if you hit the defrost button. Basically there is no good reason to ever turn the AC off. In the winter it helps with keeping the windows from fogging up and in the summer it cools the air. It will automatically decouple the compressor when cooling is not needed or also under WOT to reduce power loss. So just leave AC on and in Auto and it will do the rest.
Thread Starter
Senior Member
Joined: Feb 2025
Posts: 265
Likes: 89
From: Seattle
Currently ‘2015 S550 4matic. Previously 03 E320, ‘06 S430, ‘08 S550 4matic
Thank you superswiss.
I appreciate the explanation and agree with you.
Thanks for taking the time to respond.
take care
Chuck
I appreciate the explanation and agree with you.
Thanks for taking the time to respond.
take care
Chuck
MBWorld Fanatic!
Joined: Aug 2007
Posts: 1,844
Likes: 797
From: Pacific Northwest
2001 S600 V12 Sold, 2011 Jaguar XFR Sold, 2017 S550 4-Matic, 2018 S63 AMG Sedan
Your handle says "Seattle" so I assume you're in Seattle. Wasn't it a glorious day yesterday?? I drove with all the windows and sunroof open while running errands yesterday, the best day we have in a really long time!
And as far as climate control; I hate buring extra gas so I run my car in Auto mode with the AC turned off 90% of the time. Like Superswiss says, the AC kicks on automatically when using the defroster so that's nice. But I turn it off afterwards.
And as far as climate control; I hate buring extra gas so I run my car in Auto mode with the AC turned off 90% of the time. Like Superswiss says, the AC kicks on automatically when using the defroster so that's nice. But I turn it off afterwards.
Thread Starter
Senior Member
Joined: Feb 2025
Posts: 265
Likes: 89
From: Seattle
Currently ‘2015 S550 4matic. Previously 03 E320, ‘06 S430, ‘08 S550 4matic
Hi Carlos
Yes, I live in Lake Forest Park at the north end of lake Washington.
yesterday was beautiful..I wore a t-shirt and flip flops all day.
Thank you for the AC advice.
The main thing is knowing how the system operates. I’ll play around with settings in different situations just for the fun of it.
get ready for the thunder and hail storm coming tonight.
be well
Chuck
Yes, I live in Lake Forest Park at the north end of lake Washington.
yesterday was beautiful..I wore a t-shirt and flip flops all day.
Thank you for the AC advice.
The main thing is knowing how the system operates. I’ll play around with settings in different situations just for the fun of it.
get ready for the thunder and hail storm coming tonight.
be well
Chuck
MBWorld Fanatic!
Joined: Aug 2007
Posts: 1,844
Likes: 797
From: Pacific Northwest
2001 S600 V12 Sold, 2011 Jaguar XFR Sold, 2017 S550 4-Matic, 2018 S63 AMG Sedan
Hi Chuck, from one Park to another. I live in Normandy Park, and love Lake Forest Park. When I was looking for a house both were in our top 3 choices in the Puget Sound, along with Magnolia.
