heavy rain, then I discover fan on?

rickharrison · 10-27-2010, 06:52 AM

The other night we had a heavy rain/t-storm. In the AM I went out to get into my winter beater, and my 944S had 1 fan running. (passenger side)

No idea how long it was going.

I pulled the relay and went to work.

WTF?

smokin_944 · smokin_944's Garage

Holy moly!! How was the battery? Looks like it's trouble shooting time Rick.

Jrboulder · 10-27-2010, 01:38 PM

Thermo-fan switch? The P.O. of my car had the engine rebuilt because of this and a wrong diagnosis.

smokin_944 · smokin_944's Garage

Its trouble shooting time for 2 reasons, Jr. 1) AFAIK, on late cars both fans run on slow for a few minutes after shutting off the car, only one was running. Could be a fuse problem cause both should run at the same time. Only early cars have 1 fan running at shut off. 2) It could be the thermal fan switch OR the cooling fan relay. It depends. The way to check for this is to disconnect the thermal fan switch. If the fans continue to run, it's the cooling fan relay. If they stop, it's the thermal fan switch.

Rasta Monsta · Rasta Monsta's Garage

My S did this. . .bad relay.

rickharrison · 10-28-2010, 04:58 AM

Thermofan switch is new. hmm...relay? Will have to do the tests I suppose.

Its pretty much time to stow her away, so I'll have a look at it on the weekend.

Can the relay come apart for cleaning?

wild man · 10-28-2010, 06:06 AM

Quote:

Originally Posted by rickharrison

Can the relay come apart for cleaning?

Yes, I've done it many times. Bend the tabs out far enough to clear the board, and the plastic housings on the relays will slide right off.

AKAIK, my fans DO NOT come on when the car is turned off. The only exception to that is if they were already on when the car was turned off.

rickharrison · 10-28-2010, 06:50 AM

Isn't it just a board with 2 standard relays attached under that metal cover?

wild man · 10-28-2010, 07:21 AM

Oh, it's a metal one? I've never actually had one of those apart, but I believe that it still should not be a problem.

If you were from sin city, I would have thought that you were somebody else!

rickharrison · 10-29-2010, 06:12 AM

Well, I opened the relay. There's 4 coils within, each has its own "points" doodad when energized. None were stuck closed.

However, there's corrosion on several of the larger solders on the backside of the board....hmmm...should I clean and re-solder?

OR...is there a VW / Audi / Volvo relay that will work? (and is cheaper than Porsche)

bazar01 · bazar01's Garage

response in blue.

Quote:

Originally Posted by rickharrison

Well, I opened the relay. There's 4 coils within, each has its own "points" doodad when energized. None were stuck closed.

2 coils for slow speed and 2 coils for fast speed. Do you remember if it was running in slow speed? Then you can narrow down which coil was energized.

However, there's corrosion on several of the larger solders on the backside of the board....hmmm...should I clean and re-solder?

I think I reflowed the solder joints on mine 3 years ago and it is still working fine. I had the same problem with fans running all the time in high speed while car was running though.

OR...is there a VW / Audi / Volvo relay that will work? (and is cheaper than Porsche)

If reflowing does not fix it, you have to bite the bullet Rick.

rickharrison · 10-29-2010, 07:56 AM

I think it was in high speed running, but the battery was weakened. (probably running all night!)

It did it once before (dry day) and I tapped the relay and it shut off.

I've searched...the corrosion is likely the solder breaking down/crystallizing.

hmmm...scrape up, resolder is what I'll try.

None of the coils looked like they were stuck, as I pushed them to connect/disconnect and they sprung back normally.

Do you really need 2 coils for each speed? I was wondering if you could simply replace with 2 new separate relays instead. Maybe I'm wishful thinking.

bazar01 · bazar01's Garage

Response in blue

Quote:

Originally Posted by rickharrison

I think it was in high speed running, but the battery was weakened. (probably running all night!)

It did it once before (dry day) and I tapped the relay and it shut off.

I remember tapping on the relay as well when I was having fan always running issue. I think it was still running if I shut the car off. I used to just pull the relay out of the socket and leave it off until I drive the car again and just plugged it back in. I got tired of it and did not want to spend that amount for a stupid fan relay so I tried reflowing the solder and it worked.

I've searched...the corrosion is likely the solder breaking down/crystallizing.

hmmm...scrape up, resolder is what I'll try.

None of the coils looked like they were stuck, as I pushed them to connect/disconnect and they sprung back normally.

Do you really need 2 coils for each speed? I was wondering if you could simply replace with 2 new separate relays instead. Maybe I'm wishful thinking.

There are two fans, so Porsche put 2 coils to energize each fan in slow speed. Same thing for fast speed, one coil for each fan.

rickharrison · 10-30-2010, 05:53 AM

Well, I'll grab the FIL's solder gun and reheat/add a drop or two to each spot that looks crystallized and see what happens.

I'm still looking for a cheaper alternative to the pricey P-car relay. My "cheapness" sense is tingling...gotta be one!

rickharrison · 10-30-2010, 06:02 AM

here's a pic....

rickharrison · 11-01-2010, 11:03 AM

Am I screwed?