AWasserman

Thx Bill

Will do.

A

AWasserman

So. Before I had a chance to test the fans by switching the cables, it started working again.

I will observe and report back.

Adam

AWasserman

Here is the latest:

Randomly working then not working.

No pattern that I can detect. No environmental factor I can detect.

I can start the car, and only one fan will work, then while I'm driving it will start to work, then it will stop. I will park and when I start the car an hour later both will be working again.

So what is the component most likely to exhibit this type of random temporary failure? the Final Stage Amplifier?

Adam

TheoJ

Adam, sounds like a final stage to me. Did you resolve this? Can you let us know the outcome?

regards,
Theo

dr bob

Each fan feeds from the battery, through a dedicated fuse and dedicated wire from the battery. So the first orfer of business is to disassemble, clean, reassemble and seal/protect the auxiliarry wiring on the positive terminal at the battery. Then verify that the feeders are intact through the fuse holders. On my 1989 car these are fuses 28 and 29.

The failure in final stages is typically the FET modules, and there is no partial/erratic operation. They fail once and stay failed until replaced.

siscogts

Agree Mr bob... Replaced mines for 2,80 euro. Then replaced a good part of ICs on the control unit when fans started to run randomly, and fixed that. Then fans were only working at full speed as i turned the key. Replaced the thermoswitch of radiator, and fixed the fan system.
I am guessing if this fan system was really necessari, since the first fault.

westija

I'm worlking on mine now. Similar failure mode, but one of the fans had a bad bearing (stuck). If I turn it with the hand, it would get good for a while then stick again.
Ordered the bearings from Roger (inexpensive) and will try a surgery there before anything else.
Have a look at your bearings and if they turn freely
You might get lucky and will only be a bearing. That is what I am hoping for me.

Tim968

This thread helped me a lot, see attached pix of my little meltdown. D/S Fan was inop, P/S at full power when A/C was on. Checked section 19 in WS manual, then this comprehensive thread. Heat warp on fuse blade is ugly, scorch on fuse panel, too. ('92 ROW Ex-Japan GTS, Auto, 69km)

Thanks to all who developed this thread, now...how long should the new fuse last and what would its failure portend? Thx/Tim

AWasserman

Turned out to be final stage amplifier.

Funny story: I live in Canada. I happened to be in London England for a few days. I happened to look on eBay for a final stage amplifier. I happened to find one for about $75 Canadian dollars! In England! Normally the shipping would have made that a wash, but I managed to get it shipped to my hotel before I left for home.

Best parts deal I have ever had.

ROG100

I now stock rebuilt fan controllers for $275 8>)

2006 997.1

Hi this is my first attempt at a reply, do you happen to know the location of the controller module? I have a 2006 997.1 identical issue as the one you’re describing. Thanks

AWasserman

If (big if) it is the same as a 928, then it is under the hood mounted on the frame in front of the left side (as you are facing the car) of the radiator. It looks like this:


However you control module looks different. It looks like this:



And for all I know is in a completely different place.

You might get a better answer on the 997 forum.

Adam