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So the AC on my 2005 525i is working perfectly fine, the only issue is that the compressor won’t kick in until the engine reaches operating temperature. I’ve been dealing with it for years but I want to fix this once and for all. Any ideas as to what’s going on?
Took it to a friend of mine who codes, he found this setting for the climate control that would seem to be the most plausible setting but it’s set to inactive?
I attached 2 other settings he found but he doesn’t believe those would be related. Could they be? And is this feature pictured above opposite for some reason?
Is there anything else we could have missed? Any help/insight would be greatly appreciated to I can finally have a comfortable summer
I have never heard of that. Your coding looks fine. I wouldn't think this would be a coding issue anyway. Readout your errors in INPA and post them. I'm sure you have a AUC sensor error
Hmm, I’m going to have to go back to my friend who codes so he can get the error codes if there are any.
I’ve heard plenty about the AUC. Can someone confirm where it’s at? If I’m looking at where it should be based on what I’ve seen online, I’m either missing one, or it’s elsewhere on my car (2005 525i M54)
(please pardon how dirty my engine is. Allergy season is high where I live right now and I cannot take the time to clean it)
AUC sensor will not have anything to do with poor A/C performance. It only decides when to change to recirculate air if the car button for auto-recirculate is enable.
The Condensation Sensor lives just under the rear view mirror and that is a common failure especially if you have had a windshield replaced. This can affect A/C performance. Even if yours is complaining, I doubt that is the source of your problem.
I have not had my windshield replaced, could be the sensor had gone bad. But what’s the difference between that sensor which sounds like it only detects condensation on the windshield, and this solar sensor that sits on my dash according to this diagram from realoem? And which would be a more likely culprit to fix my delayed A/C start?
AUC sensor will not have anything to do with poor A/C performance. It only decides when to change to recirculate air if the car button for auto-recirculate is enable.
The Condensation Sensor lives just under the rear view mirror and that is a common failure especially if you have had a windshield replaced. This can affect A/C performance. Even if yours is complaining, I doubt that is the source of your problem.
You are correct with what the purpose of the AUC sensor is and does on these cars but I don't think you fully understand the BMW A/C system or maybe I don't. The IHKA works with the AUC, fogging, pressure and outside temp sensor to control heating, cooling, fogging and fresh air in the cabin. The AUC specifically works with the fogging sensor to control air flow to prevent fogging via X1816 connector (I believe it's different with high or basic but definitely different throughout the year/models on the specifics). Depending on the conditions the AUC sensor can be part of the reason why the a/c does not work as it should because the fogging sensor is not sending the signal it's looking for to A11a. Now I have seen where both AUC and fogging sensor is throwing codes or any other bad combination with those 2 sensors and the owners A/C seems to work fine just not as efficient as it should. This could be the difference in the type of errors that a sensor throws. It gets more complex as you do have the aux pump, control and heater valve to add into the equation but I think I have explained it enough. You can also pull up the diagrams to get an overall sense of what and how modules or sensors communicate with each other. BMW A/C systems are hard to troubleshoot over a forum if it's not a simple pressure, condenser, compressor or leak issue. It definitely gets more complex when you have to factor in all the other sensors that control or give needed information to provide an optimal cabin experience as BMW intended. Who knows my understanding could be completely wrong but I feel strongly about it because I have diagnosed many a/c issues on foreign cars and all of them are more or less the same and way different than troubleshooting a domestic system.
Last edited by seanjordan20; May 14, 2023 at 06:59 PM.
I have not had my windshield replaced, could be the sensor had gone bad. But what’s the difference between that sensor which sounds like it only detects condensation on the windshield, and this solar sensor that sits on my dash according to this diagram from realoem? And which would be a more likely culprit to fix my delayed A/C start?
Do not start throwing parts at the car. It is very imperative you get a readout of the errors on your car. I would only recommend replacing parts that are known bad from errors that way you're not wasting unnecessary money.
AC won’t run until engine is warmed up??
