strange interior noise at cold start
03-17-2016, 09:37 PM
#1
Rennlist Member
Thread Starter
strange interior noise at cold start
So, everything i start my car when its been sitting, i get this buzzing/rattling noise coming from the dash. Same noise whether a/c or heat is on and fan speed doesn't effect it. It goes away after a few minutes. Any idea what it could be? CCU fan maybe?
Sorry for the uber boring video....
Sorry for the uber boring video....
Last edited by GBX; 03-17-2016 at 09:56 PM.
03-18-2016, 07:36 AM
#2
Drifting
It's your CCU fan making noise. There's a very small fan attached to the back of the unit. It needs to be cleaned and lubed. There's a great step by step post "how to remove whirring sound in dash". I tried to post the link, but am unable.
03-18-2016, 08:53 AM
#3
Rennlist Member
Thread Starter
That's what I thought. But it o Ly happens at startup and then goes away. Does the ccu rear fan run for a bit at startup regardless of cabin fan setting?
03-18-2016, 09:55 AM
#4
Rennlist Member
The CCU fan starts at ignition ON and runs for up to 20 minutes after ignition OFF.
These are often covered in dust an dirt, you could possibly prolong its life by cleaning it. However, these fans wear and starts rattling, and the magnets in them weakens, so it will eventually stop and make the CCU unable to measure the cabin temperature. There are many threads about this faan in this forum.
Be sure to be seated when you hear the spare part price from Porsche.
Cheers,
Tore
These are often covered in dust an dirt, you could possibly prolong its life by cleaning it. However, these fans wear and starts rattling, and the magnets in them weakens, so it will eventually stop and make the CCU unable to measure the cabin temperature. There are many threads about this faan in this forum.
Be sure to be seated when you hear the spare part price from Porsche.
Cheers,
Tore
03-18-2016, 12:53 PM
#5
Rennlist Member
03-18-2016, 02:16 PM
#6
Rennlist Member
Thread Starter
yes. If you search you'll find people buying denso fans made for other car manufacturers and using their guts in the Porsche housing. Seems to work well for a fraction of the cost. This is the route i'll go if I can't remedy this by cleaning out the fan.
03-18-2016, 06:50 PM
#7
Drifting
The CCU fan starts at ignition ON and runs for up to 20 minutes after ignition OFF.
These are often covered in dust an dirt, you could possibly prolong its life by cleaning it. However, these fans wear and starts rattling, and the magnets in them weakens, so it will eventually stop and make the CCU unable to measure the cabin temperature. There are many threads about this faan in this forum.
Be sure to be seated when you hear the spare part price from Porsche.
Cheers,
Tore
These are often covered in dust an dirt, you could possibly prolong its life by cleaning it. However, these fans wear and starts rattling, and the magnets in them weakens, so it will eventually stop and make the CCU unable to measure the cabin temperature. There are many threads about this faan in this forum.
Be sure to be seated when you hear the spare part price from Porsche.
Cheers,
Tore
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03-19-2016, 04:15 AM
#8
Rennlist Member
See chapter Air temperature decrease over time on my DIY page:
The cabin air temperature sensor gets dirty and clogged with dust over time. The CCU fan is also known to fail after many years of service, it is used to keep an airflow over the sensor.
The CCU enclosure gets quite warm during use, and if there's no air flow over the cabin temperature sensor the CCU will be fooled to think it's very hot in the cabin. It will therefore gradually close the mixer flaps as the CCU warms up. The user often turns up the temperature setting to compensate, ending up at a very high or max setting after an hour or two. This results in an almost binary temperature control, very cold or very hot.
Cheers,
Tore
The cabin air temperature sensor gets dirty and clogged with dust over time. The CCU fan is also known to fail after many years of service, it is used to keep an airflow over the sensor.
The CCU enclosure gets quite warm during use, and if there's no air flow over the cabin temperature sensor the CCU will be fooled to think it's very hot in the cabin. It will therefore gradually close the mixer flaps as the CCU warms up. The user often turns up the temperature setting to compensate, ending up at a very high or max setting after an hour or two. This results in an almost binary temperature control, very cold or very hot.
Cheers,
Tore
03-20-2016, 09:42 AM
#9
Drifting
See chapter Air temperature decrease over time on my DIY page:
The cabin air temperature sensor gets dirty and clogged with dust over time. The CCU fan is also known to fail after many years of service, it is used to keep an airflow over the sensor.
The CCU enclosure gets quite warm during use, and if there's no air flow over the cabin temperature sensor the CCU will be fooled to think it's very hot in the cabin. It will therefore gradually close the mixer flaps as the CCU warms up. The user often turns up the temperature setting to compensate, ending up at a very high or max setting after an hour or two. This results in an almost binary temperature control, very cold or very hot.
Cheers,
Tore
The cabin air temperature sensor gets dirty and clogged with dust over time. The CCU fan is also known to fail after many years of service, it is used to keep an airflow over the sensor.
The CCU enclosure gets quite warm during use, and if there's no air flow over the cabin temperature sensor the CCU will be fooled to think it's very hot in the cabin. It will therefore gradually close the mixer flaps as the CCU warms up. The user often turns up the temperature setting to compensate, ending up at a very high or max setting after an hour or two. This results in an almost binary temperature control, very cold or very hot.
Cheers,
Tore