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Car: BMW 2007 530i (N52 Engine) 210,000KM

Details:

  • Single accessory belt for AC, Power Steering, Alternator
  • AC is clutchless variable displacement
  • Tensioner and idler pulley's replaced

Problem:

  • There is a groan in the cabin when the AC is turned on
  • The groan is exacerbated when there is load on the steering wheel while turning
  • The groan disappears when the AC is turned off
  • The groan is there when engine is cold, regardless if AC is on or off

What I've checked:

  • No play in the pulleys for any accessory
  • No groaning noise in the engine bay
  • AC performance is good
  • Power Steering performance is good
  • Power Steering fluid has been flushed

The groan sounds like a power steering groan (especially when low on fluid) from my previous experiences. However, what's throwing me off is the noise is only there when the AC is running. Can the load of an AC cause another accessory to show symptoms?

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    The AC being on will definitely change the tension in the accessory belt. So my first thought is that the power steering pump is failing. Something like the bearing that is relatively quiet until the load changes due to the AC coming on.
    – jwh20
    Nov 17 '21 at 13:06
  • That's an answer @jwh20
    – GdD
    Nov 18 '21 at 8:38
-1

According to @Kaka_oyoo on Twitter, these are some possible causes;

  1. Low level of power steering fluid.
  2. Worn bearings on any of the peripheral devices driven by the serpentine belt, namely alternators, power steering pump, water pump, or air conditioning compressor.
  3. Worn serpentine belt.
2
  • Who is "@Kaka-ooyoo on Twitter," and why should we think their view is accurate? Nov 18 '21 at 19:57
  • You really don't have to accept views from all mechanics, you could just ask your relatives... Overflow has a function where you CAN share the questions on other platforms...No one asks you to accept all answers. Nov 19 '21 at 12:53

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