Aac code 912749
Thread Starter
Junior Member
Joined: Jan 2021
Posts: 15
Likes: 1
GL 450
Aac code 912749
AAC 912749 indicates that the air quality sensor has a malfunction and there is an internal electrical fault.
Ac blows ice cold for a trip to store here and there then, on next trip Ac blows warm and moldy smell.
Afterwards it will blow ice cold, when it wants too.
Notice low pressure line gets at 200lbs when Ac is not working, when working ice cold Ac the low side is 40-50 lbs
Replaced 3 Ac compressors, 3 driers, shop has replaced compressors, vacummed and charged, Ac along with my bank card. Just need answers
If anyone have any suggestions or have had this code before. Recommendations and help us grateful.
Ac blows ice cold for a trip to store here and there then, on next trip Ac blows warm and moldy smell.
Afterwards it will blow ice cold, when it wants too.
Notice low pressure line gets at 200lbs when Ac is not working, when working ice cold Ac the low side is 40-50 lbs
Replaced 3 Ac compressors, 3 driers, shop has replaced compressors, vacummed and charged, Ac along with my bank card. Just need answers
If anyone have any suggestions or have had this code before. Recommendations and help us grateful.
Senior Member
Joined: Sep 2011
Posts: 384
Likes: 13
From: Sweden
E55 AMG V8 Kompressor 2004 E 55 AMG Type: 5,439 cc (5.439 L; 331.9 cu in) Supercharged V8 Powe
Sensor must be replaced
AAC 912749 indicates that the air quality sensor has a malfunction and there is an internal electrical fault.
Ac blows ice cold for a trip to store here and there then, on next trip Ac blows warm and moldy smell.
Afterwards it will blow ice cold, when it wants too.
Notice low pressure line gets at 200lbs when Ac is not working, when working ice cold Ac the low side is 40-50 lbs
Replaced 3 Ac compressors, 3 driers, shop has replaced compressors, vacummed and charged, Ac along with my bank card. Just need answers
If anyone have any suggestions or have had this code before. Recommendations and help us grateful.
Ac blows ice cold for a trip to store here and there then, on next trip Ac blows warm and moldy smell.
Afterwards it will blow ice cold, when it wants too.
Notice low pressure line gets at 200lbs when Ac is not working, when working ice cold Ac the low side is 40-50 lbs
Replaced 3 Ac compressors, 3 driers, shop has replaced compressors, vacummed and charged, Ac along with my bank card. Just need answers
If anyone have any suggestions or have had this code before. Recommendations and help us grateful.
of not then it is the sensor must be replaced.
Problem Is wis doesnt say anything about the location cant even find it myself and having AMG shop replacing mine next week and will be there waiting and watching
Newbie
Joined: Aug 2025
Posts: 5
Likes: 1
2016 cla
Hi, my car is having the same issue air not blowing cold air, and this code is pulling up. Did you ever fix the air quality sensor, and if so was that the fix for the a/c blowing warm air? @Benz1978 @SuperChargerE55
Last edited by t.babyshasha; Aug 21, 2025 at 02:15 AM.
Senior Member
Joined: Sep 2011
Posts: 384
Likes: 13
From: Sweden
E55 AMG V8 Kompressor 2004 E 55 AMG Type: 5,439 cc (5.439 L; 331.9 cu in) Supercharged V8 Powe
Hi, my car is having the same issue air not blowing cold air, and this code is pulling up. Did you ever fix the air quality sensor, and if so was that the fix for the a/c blowing warm air? @Benz1978 @SuperChargerE55
and I got no issues with cold / varm air at all.
I advise taking taking your car to a real AC shop can be anything from AC compressor issue, or just freon refill.
Test AC compressor at idle, Open the door and toggle the AC on / off button listen if it engage or not.
Fingers crossed
Senior Member
Joined: Sep 2011
Posts: 384
Likes: 13
From: Sweden
E55 AMG V8 Kompressor 2004 E 55 AMG Type: 5,439 cc (5.439 L; 331.9 cu in) Supercharged V8 Powe
Your most welcome, and pls take it to a real AC shop and not just a plain Stealer they don't have the same knowledge as a real AC SHOP, speaking from experience bleed me dry when had the INSIGNIA VXR with same issue "no cold air" turned out was AC pump that didn't threw any codes.
Sorry forgot to add that the other day 😜
Pls let us know how it goes
Sorry forgot to add that the other day 😜
Pls let us know how it goes
