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Randal.'s Avatar
 
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Fan stays on

On Friday I drove my son's 944 down to Costco. It was a hot day. The fan stayed on when I left the car to go into the store and it was still on when I returned.

Note: Operating temperatures were mid range, which is what I'd expect, given that a new radiator was put into this car.

When I got home the fan wouldn't go off, unless I unplugged it.

Another data point: The second fan wasn't on, even though I had been using the AC.

So I read one of the repair manuals and they suggested, if the fan remained on, that the coolant switch (in the radiator) was faulty.

So got a new switch, took the fan assembly out of the car and swapped out the coolant switch. I also tested both fans and they work.

So I put the fan assembly back into the car and when I reconnected the power, with the car cold, the fan went on.

I'm not sure what to check next, but any suggestions will be appreciated.

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Old 07-19-2009, 11:35 AM
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Time to check your fan relay.
http://www.clarks-garage.com/shop-manual/cool-01.htm
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Old 07-19-2009, 03:19 PM
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Quote:
Originally Posted by OnTheRun2 View Post

A couple of people have directed me to the clarks-garage manual. Great resource.

I'll be out there again tomorrow to see if I can now sort it out.

Thanks again,

Randal
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Old 07-19-2009, 08:00 PM
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your average wrencher...
 
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x2 on the fan relay. mine did that too, just unplugged the relay and plugged it back in. its must have been sticking and hasn't done it since
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Old 07-20-2009, 10:39 AM
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So none of the books I have show me where the relay resides.

Is it one of those relays under the dash between the main and secondary fuse boxes?

Thanks.
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Old 07-20-2009, 12:36 PM
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If you follow the link to Clark's Garage that was in my last post.
It will not only tell you where it is, it will also tell you how to test it.
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Old 07-20-2009, 01:46 PM
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The information at the clarks-garage was great, but I wasn't sure which one is the fan relay.

Maybe you can tell me from this picture.

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Old 07-20-2009, 02:20 PM
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Wish I could, but my experience with early 44s in limited. I'm sure there is someone here that can help out.
On a late 44, it is the biggest relay in the box. And the most expensive.
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Last edited by OnTheRun2; 07-20-2009 at 02:37 PM..
Old 07-20-2009, 02:27 PM
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The Horn relay with the attached fuse is Relay #9. The Fan Relay (left side radiator fan) is relay #1 and the Blower Relay (right side radiator fan) is relay #3 (directly above #9). I have replaced this relay twice on my 924S in the six years i have owned it.

...and just to confuse the issue more: IF your car is wired the same as the 87 924S, there are two more Fan and Blower relays to the right side of the (removed) glove box.
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Old 07-20-2009, 04:48 PM
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I spent some time under the dash of my early yesterday.

From memory the cooling fan relay is in the upper left in your picture. It's silver. It's just above the two unused relay position. It's on the left end next to the black relay.

You may end up pulling the relay/fuse board down to get it out. To do that I had to first remove the two screws on the auxilery fuse box. I also had to move the DME and bracket. Make sure to disconnect the battery first or sparks could fly (don't ask me how I know!).
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Old 07-20-2009, 06:23 PM
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My 86 944 n/a did the same thing, would not turn off until the battery was dead. It turned out to be the fan switch that goes into the radiator. I got it from auto zone for $12.00 and it works great.
Old 07-20-2009, 06:56 PM
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If it isn't the relay it is the Thermo-fan switch. Don't screw with buying one at Oreilly's. Just buy it from pelican for 12 buckaroos.
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Old 07-20-2009, 08:04 PM
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Quote:
Originally Posted by Randal. View Post
Hmmmm, perhaps I'm wrong, but this pic certainly looks interesting. According to Clark's, the number 3 fuse in the Aux Fuse panel is for the primary (driver's side) fan, and the number 5 is for the secondary (A/C) fan. Both of which are 16 Amp fuses.

In your pic, you show NO fuse in the number 3 position, and a "green"(?) fuse in the number 5 position. (Your pic indicates White at #1, Red at #2, etc...)

Aren't 16 amp fuses Red?



Randy
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Last edited by rcecale; 07-21-2009 at 10:57 AM..
Old 07-21-2009, 10:43 AM
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Well I now have everything working again, but, to be honest, I don't completely understand why. Here is what happened:

When I first had the "fan on" issue (passenger side) I got some advice that I should change out the temperature switch that resides in the radiator. So I did that, but managed to break the air box in the process. I did find another on Craig's list, but it took a week to get it.

After I got the entire front end back together I added the (position #3) missing fuse and nothing changed.

I then unscrewed the fuse panel (two screws) to get at the relay board. I noticed that the relay board housing was disengaged from its mounting points.

FYI the fan control relay is as shown in the picture below. I swapped out that "24" relay and again, no change.

So I put the relay panel back into it's housing, making sure it was firmly back into the positioning lugs. Also made sure the bottom tab, that holds it shut, was secured.

I then put the fuse panel back in (two screws) and hooked up the battery. No Fan (Yea!).

Then drove the car around getting it hot and on comes both fans. It seems that the passenger side fan goes faster than the drivers side fan.

Also tried the air conditioning and that immediately got the fans to cycle.

The temperature switch Bontempi sold me starts the fans at a lower temperature, which I like, as it seemed the fans wouldn't go on until the car was getting into the upper temperature ranges.

So far the car hasn't been hot enough to see the fan (or fans) working after I shut it off.

This whole process was a bit frustrating, as I wish one of my direct actions had resulted in a fix.

I'm guessing the relay board flopping around was causing some problem. The relay was housed tightly, but maybe there was a corrosion problem that I couldn't see.

I've told my son (with big feet) that he has to be careful getting into the car, making sure he didn't hit anything under the dash.

Next I need to test the old relay I took out -

Thanks to all the posters for helping out.



CORRECTION:

In the picture above the fan relay is actually the air conditioning system relay.

Likewise the AC relay is actually the rear window defroster relay.
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Last edited by Randal.; 07-31-2009 at 03:50 PM.. Reason: CORRECT A PICTURE
Old 07-31-2009, 09:30 AM
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this website has a list of all the relays and fuse's

http://944-world.com/earlyfusepanel.html
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Old 07-31-2009, 01:24 PM
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So it looks like I changed the air conditioning relay.
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Old 07-31-2009, 02:40 PM
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Well I think the problem was the air conditioning relay.

I put 12 volts across the coil and the relay clicked then started a grinding noise.

I asked an engineering friend of mine and he said, " DC relays shouldn't grind. It means its shot. Might work from time to time, but not reliable."

I also checked, at the same time, the other poles with the ohm meter and they did show 0 ohms.

So the problem has been isolated. Yea!
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Old 08-01-2009, 07:22 AM
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Randal, congrats on solving your problem. The relay you swapped out is in fact the cooling fan relay, which is a multi-use relay, Porsche number 141 951 253B (worth about 5.50 at Pelican parts). The A/C relay is the one in the number one position, on the extreme right, Porsche number 944 615 113 01. It is much taller than the cooling fan relay. Vicious posted a website that has a list of relays and fuses. Unfortunately the A/C relay and the cooling fan relay are incorrectly labelled. The A/C relay is in the first position, the cooling fan relay is in the third. There was an error in the early Porsche manuals (p.75) that has been perpetuated to this day by unsuspecting Porsche fans that thought manuals could bear no mistakes.
Old 08-10-2009, 06:51 PM
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Smokin 944 - so post #13 (above) is correctly labeled?
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Old 08-13-2009, 03:38 PM
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No, it's not. The a/c relay is on the other side of the car, so is the condenser fan relay. #1 is the cooling fan relay, #3 is for the fresh air/ heater blower motor. Not even Porsche has this right in any of the books I've seen.

Additional info: If you don't change the condenser fan relay (which sounds as if it no good, it wasn't on mine) on the passenger side, under the kick panel, to the right of the glove box, you run the risk of high pressure on the high side of the a/c system when the car is not moving, ie. not enough air passing over the condenser. It can lead to expensive repairs if you don't know how to work on a/c systems.

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Last edited by mattdavis11; 08-14-2009 at 08:41 AM..
Old 08-14-2009, 04:58 AM
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