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Author Topic: Loud noise when using environmental system  (Read 1233 times)

MikeDelta

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Loud noise when using environmental system
« on: March 21, 2017, 06:00:47 am »
Our aircraft is a 'straight' 690 with the Keith Freon kit installed.

Every time I switch on the factory air conditioning, a very loud noise can be heard. This happens when it is pressurized or not. However when pressurized, after reaching roughly 13000 ft (cabin set at 8000ft) the sound slowly fades and goes away eventually.
The previous owner told me that it could be a loose or damaged seal. It sounds like it is coming from the back of the cabin.

Has anyone ever a similar issue? I'm curious as to what the cause is and I don't really know where to look.

donv

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Re: Loud noise when using environmental system
« Reply #1 on: March 21, 2017, 09:13:46 pm »
By "factory" you mean the Keith system? Or the bleed air system?

ghancock

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Re: Loud noise when using environmental system
« Reply #2 on: March 22, 2017, 08:05:30 am »
And by noise you mean bang, squeal... :-)

Glenn
--glenn
You can't win an argument with an ignorant person,  they'll just drag you down to their level and beat you with experience.

MikeDelta

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Re: Loud noise when using environmental system
« Reply #3 on: March 26, 2017, 03:11:27 pm »
The factory unit is the regular ECU. Keith was STC'ed.

The sound is hard to describe. Can I post videos here?

Its like a piece of duct tape inside a tube through which air is blowing at high velocity.

donv

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Re: Loud noise when using environmental system
« Reply #4 on: March 26, 2017, 05:38:26 pm »
You could certainly post a link to the video.

Could it be that one of your air ducts is partially blocked, or alternatively has come loose? Do you get normal differential?

lightroombuH

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Loud noise when using environmental system
« Reply #5 on: September 10, 2019, 09:52:42 pm »
Car makes a noise while idling kinda sounds like a bearing spinning kinda like a loud trough out bearing. but goes away when i hit the clutch. its like a quiet low pitched drowning noise. any thoughts. think i should worry about it?