[RDKeysor]

Back in 2017 I posted quite a few times regarding the operation of my '92's fans.  Reading over those posts, I see that I replaced at least one of the thermal fans.  But at age 85 my memory of this is pretty dim.  Today my right-side fan continued running after shutdown.  Pulling the No. 15 fuse stopped it.  

 

So, I think I need to replace the switch.  Someone please remind me where that switch is located on the radiator and the best way to access it.  I believe it is best removed with a large socket but may yield to a conventional wrench. Thanks!

 

 

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[94SilverCab]

My fans do run for several minute after shut down, that is normal.

 

Do they continue to run for a significant amount of time (more than 2-3 minutes?)?

 

Jay

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[ds968]

My fans do run for several minute after shut down, that is normal.

 

Jay

 

Same here. 

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[MCL968]

Mine always run together after the car is shut off. Sounds like the relay is sticking. Pull it apart and clean the top and bottom contacts before you replace the fan switch.

 

But, in answer to your question, the switch is on the right side of the radiator (with you facing the engine) or left side of the car, under the top radiator hose. If you replace the switch, go with the Vanagon unit that goes on at a lower temp. DO NOT overtighten it, you will crack the radiator. Use a torque wrench and follow the torque specs. Then make sure you bleed out the air in the system using the bleeder on the top radiator hose gooseneck bu the fuel injector rail.

 

Good Luck, not a tough job but one that will make a difference. 

 

M-

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[RDKeysor]

As a couple of responders said, my car also almost always has the fan continue to run for a minute or two after shutdown.  I am in Florida.  However, on this occasion the fan simply continued to run much longer than normal and was only stopped by pulling fuse no. 15.  I have continued to drive the car, and I am somewhat surprised but happy to say the other fan runs for a couple of minutes after shutdown.  I was under the impression that the second fan ran when the AC unit was operated, but I haven't been using the AC during moderate weather.  I have purchase a new thermal fan switch with with washer and find that I have a deep (not metric) socket that fits the switch, this probably purchased the last time I changed it.  I would appreciate receiving the proper torque setting.

 

And finally, Booster suggested that I clean out the fan relay because that may be the problem rather than the thermal switch.  Hope someone will tell me where that relay can be found.  Thanks to all of you who took time respond to my query.

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[Waylander]

If you have air con, its the massive silver double size relay at the top of the fuse box, be gentle with it they are nearly $400 new

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[RDKeysor]

And now the report.  I explained here a couple of weeks back that the right fan in may '92 continued to run long after shut down, stopped by removing fuse no. 15.  I then did a consult here on the location of the thermal fan switch, etc., acquired Beck/Arnley switch, drained radiator, removed the Wahler  85/93 degree C switch I had installed about 10,000 miles ago.  My records indicate that I had changed the switch previously.  Put in the Beck/Arnley unit and have been using the car for about a week.

 

The first couple of times I drove the car it was relatively cool and did not turn on after engine shut off.  With the old Wahler switch, the fan or fans would generally run for only a minute or two after shut off. Now, if the fan (s) activate after shut down, the fans switch on and off for quite a while.  I clocked them at five minutes from turn on to turn off today after a seven mile, stop and go trip with the temperature about 80 degrees.  That seems way to long fan operation to me.  I thinking about acquiring a different brand switch and installing it before I button up the underside of the car.  I had drained the radiator by pulling the hose at the right front, using a very large container to catch the inevitable rivulets that happen when you drain these cars.  Couldn't find the drain switch for some reason.  I was prepared to use the rubber glove trick someone wrote about on this forum in an effort to control the drainage but pulling the hose worked OK.  Again, thanks for those who responded.  At age 85 I think I'm about ready to cease doing my own work on a car I've now driven daily for nearly 24 years.

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[Velocity]

[...]

 

OK.  Again, thanks for those who responded.  At age 85 I think I'm about ready to cease doing my own work on a car I've now driven daily for nearly 24 years.

 

I can't help too much with your fan switch issue, but would also recommend cleaning the relay if you haven't already.    It's located at position G10 (see attached diagram) in the relay/fuse box under the hood near the windshield - at the other end of the box where you pulled fuse 15.  :-)     One more fact on the fan operation - the fan will run WHENEVER you have the AC compressor on (even with key on/engine off).

 

Also, kudos for doing mechanical work on your car at 85 years old that the vast majority of people half your age wouldn't be capable of.     

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[John]

Check out "968 Cooling ..." file found in 1st post in "Electrical Trouble-shooting the 968 Cooling System" located in DIY/Electrical. There's a section on the relay, might be useful.  John .

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[Velocity]

Check out "968 Cooling ..." file found in 1st post in "Electrical Trouble-shooting the 968 Cooling System" located in DIY/Electrical. There's a section on the relay, might be useful.  John .

 

Direct link to the thread John refers to above is https://www.968forums.com/topic/9029-ele...ng-system/

 

Also - IF the relay turns out to be the root cause, there is a solid state (ie, likely more reliable) version of the relay that has built-in diagnostic capabilities for roughly half the "new relay cost" Waylander mentioned earlier in the thread at https://www.ftech9.com/new-products/evm5sg4dqli142yinandvtb66x27i0 

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[Waylander]

Is that not the DME relay from F9, not the big double cooling fan relay

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[Velocity]

Is that not the DME relay from F9, not the big double cooling fan relay

 

They sell both a replacement DME relay and a fan relay.   

 

The link I'd posted above seems to not be working anymore, but you can find both relays on their site at https://www.ftech9.com/new-products?cate...+Relays%29

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[Peter]

I apologize if I posted in the wrong thread.

 

Are the radiator fans supposed to work when the thermo switch is disconnected and no key in the ignition? I searched a lot, but could not find the answer to this exact question.

The cooling fans on my car were coming on at low speed of their own when the car was stone cold and no keys in the ignition.

 Last time I parked the car in the garage, nothing suspicious, then I found the battery dead a few days later (I was away). As soon as I charged the battery and connected it, both fans started running (at high speed this time). What puzzled me was the fact that the fans run at high speed exactly the same with the old switch connected or disconnected. And they run the same with the new thermo switch (Wahler 85/93C, which I bench tested and it was good).

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[oppositelock]

The fans will only come on via the temp switch in the radiator or when the air con compressor button is pushed. Sounds like you have a fan relay sticking. Just above your posting are two from Velocity with very good troubleshooting and relay information.

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[Peter]

The fans will only come on via the temp switch in the radiator or when the air con compressor button is pushed. Sounds like you have a fan relay sticking. Just above your posting are two from Velocity with very good troubleshooting and relay information.

You are correct. When testing the relay on the bench, I found that the TS (ground) was always present, meaning, there was no need for the signal from the radiator's thermo switch to turn on the fans.

I purchased a new (traditional) relay, which fixed the problem. Regarding the SSR from the link above, it is sold out.

I also opened the old relay (which, looked perfect, in terms of physical conditions, meaning, no corrosion or visually burnt/suspicious components) and I think I narrowed the issue down to two diodes, which are located between V1 and V2 switches (relays). When tested on the board, those two diodes read 0.04V in both directions, which was puzzling, because that was neither open nor shorted. I do not want to remove them until I find the diode replacements.

Does anybody know the models of those diodes (or the modern equivalents)? I cannot read anything from the diode bodies that are currently still soldered to the relay PCA.

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[unknown4u]

Can you post a photo?

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