slight buzzing or humming from HVAC
Thread Starter
Racer
Joined: Dec 2014
Posts: 473
Likes: 6
slight buzzing or humming from HVAC
After i shut down my 964 i hear a slight humming or buzzing coming from the havoc control area. nothing is blowing out of the vents that i can tell but i hear something. enough that its annoying and I'm afraid of battery drain if something is not shutting down. i disconnect the battery and it stops, hook it back up and its still quiet. start the car and shut it down and the buzzing comes back.
any ideas?
Thanks in advance.
any ideas?
Thanks in advance.
Nordschleife Master
Joined: Jul 2007
Posts: 5,613
Likes: 52
From: DFW, TX
It's the fan on the back of the CCU that's starting to die.
Here's a thread.
https://rennlist.com/forums/964-foru...aning-diy.html
Here's a thread.
https://rennlist.com/forums/964-foru...aning-diy.html
Nordschleife Master
Joined: Jul 2007
Posts: 5,613
Likes: 52
From: DFW, TX
Here's another thread.
https://rennlist.com/forums/964-foru...rmal-cost.html
This fan on my car is shot and stupid loud. I haven't taken the time to replace or repair it. Instead I disconnected its plug from the back of the CCU so it no longer runs. Since the only time I use my HVAC is on Max Cold, the lack of fan operation doesn't affect my climate control performance.
https://rennlist.com/forums/964-foru...rmal-cost.html
This fan on my car is shot and stupid loud. I haven't taken the time to replace or repair it. Instead I disconnected its plug from the back of the CCU so it no longer runs. Since the only time I use my HVAC is on Max Cold, the lack of fan operation doesn't affect my climate control performance.
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This page might be helpful. Scroll down to:
"CCU fan whine or unpleasant sound in dashboard
Some might think they have a very noisy clock in the dashboard, but this is often a failing CCU fan. The fan needle bearings wear out, and the fan may be very dirty. You could try to clean the fan rotor, but be prepared to change it, a repair may not last very long. See the details page for more on this."
-Luccia
"CCU fan whine or unpleasant sound in dashboard
Some might think they have a very noisy clock in the dashboard, but this is often a failing CCU fan. The fan needle bearings wear out, and the fan may be very dirty. You could try to clean the fan rotor, but be prepared to change it, a repair may not last very long. See the details page for more on this."
-Luccia
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Thread Starter
Racer
Joined: Dec 2014
Posts: 473
Likes: 6
It does shut off after 10-20 minutes. When I first posted I wasn't aware of how long it ran after I turned off the ignition. just never noticed because I never sat in the car long after I shut the ignition off.
Only after I installed a stereo did I notice it. It sounded like slight feed back and since I just wired a new head unit I thought something was humming from that. Pulled the head unit out and then I noticed it was from the hvac control.
All functions normally heat/AC and blower blows fine.
I forgot where but somewhere I read this afternoon that it's normal to run for 15-20 minutes after you turn off the ignition.
Is that right? If so then I may not have a problem. Just never noticed before because I've only had the car since December.
It's not really loud. But noticeable when everything is quiet. But not annoying.
Only after I installed a stereo did I notice it. It sounded like slight feed back and since I just wired a new head unit I thought something was humming from that. Pulled the head unit out and then I noticed it was from the hvac control.
All functions normally heat/AC and blower blows fine.
I forgot where but somewhere I read this afternoon that it's normal to run for 15-20 minutes after you turn off the ignition.
Is that right? If so then I may not have a problem. Just never noticed before because I've only had the car since December.
It's not really loud. But noticeable when everything is quiet. But not annoying.
Thread Starter
Racer
Joined: Dec 2014
Posts: 473
Likes: 6
This page might be helpful. Scroll down to:
"CCU fan whine or unpleasant sound in dashboard
Some might think they have a very noisy clock in the dashboard, but this is often a failing CCU fan. The fan needle bearings wear out, and the fan may be very dirty. You could try to clean the fan rotor, but be prepared to change it, a repair may not last very long. See the details page for more on this."
-Luccia
"CCU fan whine or unpleasant sound in dashboard
Some might think they have a very noisy clock in the dashboard, but this is often a failing CCU fan. The fan needle bearings wear out, and the fan may be very dirty. You could try to clean the fan rotor, but be prepared to change it, a repair may not last very long. See the details page for more on this."
-Luccia
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Rennlist Member
Joined: Apr 2004
Posts: 2,569
Likes: 537
From: Oslo, Norway
Luccia, thanks for the reference. A new CCU fan is almost completely quiet. Old ones rattle and hum. The magnets wear out (demagnetizes) over time, as well as the bearings. This will eventually stop the fan, or it may only start once in a while.
Cheers,
Tore
Cheers,
Tore
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Thread Starter
Racer
Joined: Dec 2014
Posts: 473
Likes: 6
Any noise at all is a sign it's about to start failing?
Rennlist Member
Joined: Apr 2004
Posts: 2,569
Likes: 537
From: Oslo, Norway
The fan motor is not completely silent, and noise is sometimes heard, depending on state and how dirty it is. But, it should not be loud.
The fan runs for up to 20 minutes after ignition has been on for more than ten seconds or so. If the ignition has been on for only a few seconds, the fan stops (and CCU shuts down) immediately.
A complete power off (disconnect fuse 1 or car battery) will of course stop both the fan and CCU, as well as reset the power-off timer.
Cheers,
Tore
The fan runs for up to 20 minutes after ignition has been on for more than ten seconds or so. If the ignition has been on for only a few seconds, the fan stops (and CCU shuts down) immediately.
A complete power off (disconnect fuse 1 or car battery) will of course stop both the fan and CCU, as well as reset the power-off timer.
Cheers,
Tore
Nordschleife Master
Joined: Feb 2007
Posts: 5,095
Likes: 3
From: Cheshire, UK
