Many BMW owners have encountered a peculiar issue: the air conditioning compressor engages even when the snowflake button is off, particularly in humid conditions. This can be frustrating, especially when you prefer to control the AC manually. One user, facing this exact problem with their BMW, turned to coding in search of a solution and explored using tools like Carly and VEEPeak for coding.
The original poster, “Surly73,” described the problem clearly: “In certain humidity conditions, the IHKA will still turn on the AC compressor without illuminating the snowflake button.” They had already tried coding AC_NICHT_EIN_BEI_AUTO and OFF_MEMORY in the IHKA (Integrated Heating and Air Conditioning) module, but the issue persisted, albeit less frequently. Even with these settings, the “hidden” AC would activate, especially during summer evenings with open windows and the system turned on for air circulation.
Surly73’s goal was precise: to prevent the AC compressor from activating automatically, except when the front defrost button is engaged. Currently, with AC_NICHT_EIN_BEI_AUTO coded, achieving defrost with AC requires pressing both the defrost and snowflake buttons, a minor inconvenience.
Further research on a BMW forum revealed potential coding parameters related to “fogging prevention”:
3001 Funktionskodierung (Function coding), 29 BESCHLAGSVERMEIDUNG (FITTING AVOIDANCE??) (fogging prevention)
AKTIV (Active) = 01 (default)
Comment = OPTIONS
NICHT_AKTIV (not active) = 00
changed to nicht_aktiv
3001 Funktionskodierung (Function coding), 29 KMV_AKTIV_BESCHLAG (KMV ACTIVE BRACKET) (fogging prevention)
AKTIV (Active) = 01 (default)
Comment = OPTIONS
AKTIV (Active) = 01
NICHT_AKTIV (not active) = 00
changed to nicht_aktivThe suggestion was to deactivate these two “fogging prevention” settings (BESCHLAGSVERMEIDUNG and KMV_AKTIV_BESCHLAG) to potentially resolve the unwanted AC compressor activation. The logic is that these settings might be triggering the AC in humid conditions to prevent window fogging, even when not explicitly requested.
This is where tools like Carly and VEEPeak become invaluable. Using Carly with a VEEPeak OBD2 adapter or other compatible OBD2 readers, BMW owners can access and modify these advanced coding parameters within their car’s IHKA module.
To implement this potential solution using Carly with VEEPeak, you would generally follow these steps:
- Connect: Plug your VEEPeak OBD2 adapter into your BMW’s OBD2 port.
- Pair: Establish a Bluetooth connection between your smartphone/tablet running the Carly app and the VEEPeak adapter.
- Identify Car: Let the Carly app identify your specific BMW model.
- Access Coding: Navigate to the “Coding” section within the Carly app and select the IHKA module.
- Expert Mode (if necessary): Depending on the Carly app’s interface and your BMW model, you might need to access “Expert Mode” to find the specific “fogging prevention” parameters.
- Modify Parameters: Locate
BESCHLAGSVERMEIDUNGandKMV_AKTIV_BESCHLAGwithin the coding options. Change their values from “AKTIV” (Active) or “01” to “NICHT_AKTIV” (Not Active) or “00”. - Code: Apply the coding changes using the Carly app.
- Test: Monitor your BMW’s AC behavior, especially in humid conditions, to see if the unwanted compressor activation is resolved.
It’s important to note that modifying these “fogging prevention” settings might have other effects on the IHKA system’s behavior. Surly73 rightly pondered the potential impact, especially on the defrost function in non-AC mode. Careful testing and observation after coding are crucial to ensure the changes align with your preferences.
In conclusion, for BMW owners struggling with the automatic AC compressor issue, exploring coding options with tools like Carly and VEEPeak offers a promising avenue for customization. Deactivating the “fogging prevention” settings may provide the desired control over the AC system. However, always proceed with caution, research thoroughly, and understand the potential consequences of any coding modifications you make to your vehicle.
