BMW Questions? Ask a BMW Repair Expert for Answers.
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Well, this is a computerized HVAC system that works based on multiple input signals from a variety of sensors and modules. So, while the simple answer to your question as to 'why the compressor won't engage unless hot wired' would be 'because it's not getting power from the HVAC control module', it still would not explain the logic behind it. Do you by any chance have access to a scan tool capable of interacting with the HVAC module in your BMW? If so, we could determine more clearly what's preventing the HVAC module from turning the compressor on.
Juan thanks, ***** ***** I was waiting for an answer I found the problem. The green light snow flake button on the dash needed to be depressed to activate the compressor. Since that button was missing I assumed the recirculate button was the AC button because it has a green light also.
Thanks but I 'll not need help on this one.