About a week or so ago, my AC started cutting out in my 2012 S550. The red "Auto" LED stayed lit, but there was just the slightest breeze coming out of the vent. Initially, it was intermittent dropouts, but now it's intermittent operation. I generally have my AC set to LO and run it all day in the Summer. It hasn't been unreasonable hot during this period, averaging between 85° and 95° and I haven't been able to detect any pattern.

Any thoughts on what might be the cause or have some troubleshooting tips to help me diagnose it?


Thanks,
MB

 

low gas is a normal cause of AC not behaving - its normal for cars to lose up to 10% gas per year.... its far less known these days as variable rate compressors cope better with low gas - the older clunk and its on clutch driven ones would give up all the time,

of course had you described your point more clearly it might help, as you appear to infer an air flow, rather than an air temp issue. If its the fan not behaving, this can be due to water ingress with leaf litter and crud blocking the drains at the sides of the windscreen bottom

 

It does sound like the fan blower motor died and as BOTUS indicates it is usually due to water leaks at the windshield or from a clogged drain. Keep us posted.

 

Blower motor and controller get replaced as a set.

I got to do this twice during my time with a 221.

 

Ugh... And I'm sure that wasn't cheap.

I think it's rapidly becoming time to get out of this thing.


Thanks,
-MB

 

Meh... Easy work. Buy parts and install. First time doing it in under an hour.

 

Out of all the things...the blower motor assembly is one of the easier things to replace and not overly bad priced. (It is under the dash, plastic panel above passenger footwell.

 

https://www.fcpeuro.com/products/mer...mer-2218202714

 

My comment isn't out of an unwillingness to do the work. My mechanic warned me that after about 10 years the repairs start increasing and I just had to replace one of the Air-matic Struts, so this coming so soon after got my anxiety up.

That said, I was monkeying around with settings and as soon as I ticked the "Mono" checkbox, the blower started pushing out blissfully cool air again and it hasn't failed for multiple days. At the time, I was just looking for a way to open the vents to let in outside air, so I don'r even know what "mono" means, but it's working. Does this help anyone diagnose my issue or is it just a coincidence and I'm still going to need to replace the blower?


Thanks again,
MB

 

I'm religious about keeping those drains clear. I check/clean them at least once per month.

It does appear to be a blower issue, as I could feel the slightest bit of cold coming out of the vent. As I wrote in another reply, when I ticked the "Mono" menu setting, the blower started going and hasn't quit in days. Since that earlier reply, I searched the Operator's Manual and learned that it refers to "control climate control centrally." Not sure how this might have had anything to do with my issue, but for the time being I have cool air. Unless I hear differently, I'm going to assume this is temporarily "repaired" and move on with my life. Thanks to all who've chimed in with suggestions.


-MB

 

mono is in the manual - but rather than being at the top on its own where it belongs, its hidden in endless confusing drivel over multiple pages of rubbish - it means make the drivers control work for the whole car

so if a passenger pushed theirs to flat out half the car can get full heat and the driver could be on 16 (65) then the car will heat up (as the heat outputs more than the AC can) - but with mono, the car will follow the drivers side temp setting and fan speeds

auto is also a waste of space - as it revs the fan up and down like some moron - best settings are

ensure auto flow and auto fans are disabled both sides
open all vents on the whole car to flat out and direct face vents to flow to warm hands, arms and chest
set the air flow arrows both sides to large arrows screen, face and feet
set the temp both sides to "21" (70)
set fan speed to "2" (and maybe 3 if its very adverse outside)
set the hidden air flow setting to feet at "-1"
set the hidden setting of random stupidity out the vents to "diffuse"


if you have rear AC as well,
get it off auto
open vents full and again aim all fours face events to arms and chest
set temp both sides to 21C
set fans both sides to 2

AND NEVER EVER TOUCH THE SETTINGS FROM WHEN YOU DRIVE OFF THE FORECOURT BRAND NEW - TILL THE CAR GETS SCRAPPED 7 - 20 YEARS DOWN THE ROAD