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Discussion Starter · #1 · (Edited)
Hi everybody. I am looking for your knowledge and help. My Infiniti Q50 Red Sport that has 5,000 miles makes this single loud weird thump noise when starting the car cold first thing in the morning after the car has been parked for several hours, it never happens at other times. The sound appears at second 7. Is this normal?.

This is the video

 

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I never heard that noise on mine. I have 6k miles for reference. Where does it appear under hood(?) to be coming from?
 

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AC compressor clutch kicking in (engaging)?
 

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Do you think that may be the cause?. I read that the DAS (Direct Adaptive Steering) also makes noise but I don´t know if this is my case
Not sure I don't have DAS.
 

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Almost sounded like an amp or something turning on, I’m not sure. But I’d take it to the dealership and leave it over night. Might be nothing, but it’s better to know.
 

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Discussion Starter · #8 ·
AC compressor clutch kicking in (engaging)?
I tried what you said. Every time I turn on and off the AC I get that same thumping sound but not as loud as in the morning. My question is: My car has always the AC off so when I turn on the car in the morning should the AC clutch still engage even if the AC is off?
 

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Do you think that may be the cause?. I read that the DAS (Direct Adaptive Steering) also makes noise but I don´t know if this is my case
Was your parking brake set when you took that video? You have a Master Warning light and Brake Warning light on your display.

I haven't heard of DAS making that kind of noise and mine doesn't make that noise. Perhaps it's the steering clutch if you have DAS but hard to say. If you generate a similar sound by switching the A/C on and off, I'd think that's where to start. Have you scanned the car for DTCs with an OBCII scanner?
 

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Discussion Starter · #10 ·
Was your parking brake set when you took that video? You have a Master Warning light and Brake Warning light on your display.

I haven't heard of DAS making that kind of noise and mine doesn't make that noise. Perhaps it's the steering clutch if you have DAS but hard to say. If you generate a similar sound by switching the A/C on and off, I'd think that's where to start. Have you scanned the car for DTCs with an OBCII scanner?
Yes, the parking brake was engaged. Does the AC clutch engages in the morning when you first start the car even when you have it in off mode?
 

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Yes, the parking brake was engaged. Does the AC clutch engages in the morning when you first start the car even when you have it in off mode?
AC compressor clutch engages in auto mode depending on several conditions and when defrost is enabled.
 

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Yes, the parking brake was engaged. Does the AC clutch engages in the morning when you first start the car even when you have it in off mode?
What specifically do you mean by "off mode"? What specific switch are you using to turn the A/C system on and off?
 

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Discussion Starter · #13 ·
AC compressor clutch engages in auto mode depending on several conditions and when defrost is enabled.
So the AC compressor always engages when starting the car no matter if the AC is turned off?
 

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Discussion Starter · #14 ·
What specifically do you mean by "off mode"? What specific switch are you using to turn the A/C system on and off?
So the AC compressor always engages when starting the car no matter if the AC is turned off?. I mean by off mode that the AC is turned off
 

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So the AC compressor always engages when starting the car no matter if the AC is turned off?. I mean by off mode that the AC is turned off
You didn't answer my question. Which switch are you turning off the A/C with? #2 or #6?

Rectangle Font Parallel Computer monitor accessory Technical drawing
 

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Going down a different rabbit hole...

To me, it sounds like a blend door is stuck, so the sound is the actuator trying to move the blend door into position, and can't.

Try the A/C in different modes and see if the sounds repeats to confirm.
 
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Going down a different rabbit hole...

To me, it sounds like a blend door is stuck, so the sound is the actuator trying to move the blend door into position, and can't.

Try the A/C in different modes and see if the sounds repeats to confirm.
Hadn't considered that but it might be a blend door.
 

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one of the wastegates hanging up momentarily before full open?
 

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Sounds internal to the cab to me. The OP should experiment with changing the vents to see if he can replicate the sound.
 
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