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Porsche specialists buying, selling, servicing | 911virgin | Uxbridge

Fan whistle diagnosis

O

orangefender

Silverstone
Joined
25 Oct 2014
Messages
141
Hi,

Hoping someone on here has had a similar issue.

I have what I can only describe as a boiling kettle type whistle coming from one of the heating system fans. My car is non-AC.

I suspect the fans in the front behind the firewall from what I've read on various posts but don't want to go through pain of getting to them only to discover that's not the problem!

This is what I observe:

- Whistling only audible when fan is set 2 - 4 on fan speed control (with corresponding increase in volume)
- When car turning off a different much quieter humming almost buzzing like sound can be heard from coming from behind the heater controls (suspect CCU)
- Good strong heat coming from heater generally and no issues other than whistle.
- Whistle not audible from luggage compartment
- Faint whistle of similar pitch heard from rear outside of car

Based on the above where should I start?
 
That does sound like the fans behind the firewall. I think it is the bearings in them. If I have to swap the evaporator on the A/C out I will replace both as a precaution as they all fail eventually. Problem is once you hear it, you always hear it. It's not exactly loud though. Live with it?
 
I would agree it's play in one of the fan bearings. I replaced both fans and one occasionally makes a similar noise , the clearance between the fan and filter is pretty tight allowing occasional rubbing contact. It varies with temperature and fan speed. If you pull the filter you may find signs of contact, a Stanley knife solved my problem after a gentle paring of the plastic.
 
The sintered brass fan bearings wear out and will eventually seize completely. Fuse 1 will blow due to the excessive motor current. Changing the fans is not very, and a bit fiddly if you haven't done this before.
Good quality motors with fan cage are available as spares at Dansk/JP Group. Original fans costs a lot more.

The humming behind the CCU is a worn-out CCU fan. Replacement here:
https://www.bergvillfx.com/index.php/fan-porsche-964-993-climate-control-unit.html
Do NOT buy the JP Group CCU fan spare, they rattle way more than a worn-out original fan.
Cheers,
Tore
 
Thanks guys appreciated.

I'm going to replace the front fans first and have ordered a pair of the Dansk units. Thank heavens for after market suppliers!

Hopefully I'll manage to fit myself over the weekend - wish me luck!
 
From memory iirc the petrol tank gets in the way of fan removal. I changed them when replacing the evaporator. cutting up the fans as mentioned in the Rennlist article is not a good idea the screws are not that difficult to remove, use a magnetised screwdriver or grab with a magnetic wand.
I think you can release the tank to move it slightly forward.
I followed ths article:- https://www.pelicanparts.com/techar...eplacement/65-ELEC-Evaporator_Replacement.htm
There were a few differences but nothing major.
I found some fans at a reasonable price at Eurocarparts, orientation of the new fans and routing the wiring is a bit tricky.
 
ToreB, thanks for the P-Car link. Seriously considering doing this myself over the winter months. A few weekends should do it. :grin:
 
orangefender said:
Hi,

Hoping someone on here has had a similar issue.

I have what I can only describe as a boiling kettle type whistle coming from one of the heating system fans. My car is non-AC.

I suspect the fans in the front behind the firewall from what I've read on various posts but don't want to go through pain of getting to them only to discover that's not the problem!

This is what I observe:

- Whistling only audible when fan is set 2 - 4 on fan speed control (with corresponding increase in volume)


- When car turning off a different much quieter humming almost buzzing like sound can be heard from coming from behind the heater controls (suspect CCU)
- Good strong heat coming from heater generally and no issues other than whistle.
- Whistle not audible from luggage compartment
- Faint whistle of similar pitch heard from rear outside of car

Based on the above where should I start?
Click to expand...

Hi Orangefender sorry for the hi-jack but I have been trying to reply to your DM's but they are stuck in my outbox. The cover is in non-porsche items for sale so perhaps go take a look and reply to the add then I can reply back. I've reached out to 911uk and am waiting to hear why my replies seem to be stuck.
 
Fulla said:
orangefender said:
Hi,

Hoping someone on here has had a similar issue.

I have what I can only describe as a boiling kettle type whistle coming from one of the heating system fans. My car is non-AC.

I suspect the fans in the front behind the firewall from what I've read on various posts but don't want to go through pain of getting to them only to discover that's not the problem!

This is what I observe:

- Whistling only audible when fan is set 2 - 4 on fan speed control (with corresponding increase in volume)


- When car turning off a different much quieter humming almost buzzing like sound can be heard from coming from behind the heater controls (suspect CCU)
- Good strong heat coming from heater generally and no issues other than whistle.
- Whistle not audible from luggage compartment
- Faint whistle of similar pitch heard from rear outside of car

Based on the above where should I start?
Click to expand...

Hi Orangefender sorry for the hi-jack but I have been trying to reply to your DM's but they are stuck in my outbox. The cover is in non-porsche items for sale so perhaps go take a look and reply to the add then I can reply back. I've reached out to 911uk and am waiting to hear why my replies seem to be stuck.
Click to expand...
Fulla - when you sent a PM, they will appear in your Outbox. When the recipient reads your PM, it will appear in your Sent Items. So, you can conclude, he hasn't read it yet :) .
 
Sorry rarely login hence delay seeing messages but now seen, thanks.

By way of update, started to investigate further but couldn't hear any whistling from the fans even with the cover removed. That led me
to investigate further and was slightly embarrassed to discover the culprit was the closed flap behind the passenger side vent! As soon as it opened the whistling stopped.

Presumably just doesn't close like it once did. Though interestingly the driver's side cent has far less airflow than the passenger and central vents - is that usual?
 
^^ OF, I've always noticed the passenger side of the windscreen, has cleared before the drivers, I was never sure as to whether it was a fault/anomaly or that the ventilation was bias toward a left hand drive vehicle?? What do the more informed on here think??
 
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