Radiator fan

[Starter986]

Took a drive to Big Bear last weekend, and the car was running a little hot. I have Torque on a tablet and was monitoring the coolant temperature. It does put the dash gauge to shame. Anyhow... driving up the backside the temperature was reading 230+. When I was on the straights it dropped. The coolant light never came on.

Next day checked the fan operation (car cold, engine running, AC on) and only the passenger side fan came on. OK. So I ran the tests (relays "clicked"... swapped relays) and no driver side fan. Removed all relays and jumped them. The passenger side passed. Driver side... nothing. So I'm leaning towards a failed fan.

Correct me if I'm wrong: Jumping the relays with no fan action reveals a failed fan. Isn't jumping the relays to see if the fan works the same as disconnecting the fan harness and testing at the actual fan?

There are fans for sale on EB, and with the resistor attached. They're running ~$60 shipping included. I found this fan:https://www.carparts.com/cooling-fan-assembly/replacement/rp16090001

With shipping... ~$65.

Assuming I've no more tests to run... do I buy used or the new unit?

If I am buying a unit, new or used, I'd open to purchasing from a forum member same terms.

Thank you for your consideration.

[steved0x]

>Next day checked the fan operation (car cold, engine running, AC on) and only the passenger side fan came on.

Most common cause of this is failed low speed resistor.

There are 4 relays for the fans, a high speed relay and a low speed relay for each side. Your post doesn't say if you tried both relays on the failed side. If you jumped the high speed relay and got no fan, that sounds like the fan. But if you jumped only the low speed relay, then it could be a failed resistor which is very common and the way to test would be to jump the high speed relay.

I actually have a switch on my Boxster that grounds pin 85 on the two high speed relays so I can run the fans on high when I am on track.

Here are a couple of threads with more details:
https://986forum.com/forums/diy-project-guides/61513-diy-manual-radiator-fans-control.html
https://986forum.com/forums/diy-project-guides/76140-diy-manual-radiator-fan-switch-w-oem-switch.html

[Starter986]

Originally Posted by steved0x

>Next day checked the fan operation (car cold, engine running, AC on) and only the passenger side fan came on.

Most common cause of this is failed low speed resistor.

There are 4 relays for the fans, a high speed relay and a low speed relay for each side. Your post doesn't say if you tried both relays on the failed side. If you jumped the high speed relay and got no fan, that sounds like the fan. But if you jumped only the low speed relay, then it could be a failed resistor which is very common and the way to test would be to jump the high speed relay.

I actually have a switch on my Boxster that grounds pin 85 on the two high speed relays so I can run the fans on high when I am on track.

Here are a couple of threads with more details:
https://986forum.com/forums/diy-project-guides/61513-diy-manual-radiator-fans-control.html
https://986forum.com/forums/diy-project-guides/76140-diy-manual-radiator-fan-switch-w-oem-switch.html

Hi Steve,

Thank you for the input. Oh... I read a lot of threads. A lot. I know that I'm not the first person with a failed fan... so I rely on the seqarch feature first before turning to the forum.

I jumped all relays... just to be certain.

The driver side high speed fan, when jumped... silence.

Once I get this repaired I'm going to go the switched fan route.

That said...

Watcha think? Do I purchased used, and hopefully from a lower mileage specimen, or do I purchase that aftermarket new one for ~$65?

Thank you.

[piper6909]

Did you pull the plug at the fan and check with a test light to see if there's power at any of the pins? I'd make sure I have power at the fan before buying another one.

[Starter986]

Originally Posted by piper6909

Did you pull the plug at the fan and check with a test light to see if there's power at any of the pins? I'd make sure I have power at the fan before buying another one.

I did not. Can you point me to the instructions for that procedure? Is that something that can be donw without removing the bumper cover or the wheel well plastic?

Thanks, Pipe.

[piper6909]

Originally Posted by Starter986

I did not. Can you point me to the instructions for that procedure? Is that something that can be donw without removing the bumper cover or the wheel well plastic?

Thanks, Pipe.

According to this video, you can get to it by removing the inner wheel well. You won't have to remove the bumper cover.

https://www.youtube.com/watch?v=XsPeDvJXEUs

In this video Burner's high speed was working, so he determined that he had a bad ballast resistor. In your case, if NO speed works after you jump the pins, it could be bad wiring or a connection or it could be the motor. But I'd check the wiring first.

Here's another link that shows you how to access the fans:
http://www.pedrosgarage.com/Site_3/Replace_Radiator_Fan.html

Another fairly easy test is to see if the fan spins freely.

[Starter986]

Originally Posted by piper6909

According to this video, you can get to it by removing the inner wheel well. You won't have to remove the bumper cover.

https://www.youtube.com/watch?v=XsPeDvJXEUs

In this video Burner's high speed was working, so he determined that he had a bad ballast resistor. In your case, if NO speed works after you jump the pins, it could be bad wiring or a connection or it could be the motor. But I'd check the wiring first.

Here's another link that shows you how to access the fans:
Replace Radiator Fan

Another fairly easy test is to see if the fan spins freely.

Thank you, Pipe. That Burner vid is one of the vids I watched and recall my horror at the exactly one minute mark... when he begins strong arming out the unit. The closer arrives at 17:42 when after summing up with, "So that's it. That's the whole process" he hits with, "You put everything back in the way it came out".

While I was testing the relays... jumping... running car to temp... etc. I had a constant mental loop of that video and hoping that wasn't the route I would have to take.

Snuck my hand under... fan spins freely.

Tomorrow morning I'll lift that side... peel back the liner... see if I can't access the electrical connection... to which I'll run 12V... without having to take off a bunch of parts.

Have a nice evening.

[piper6909]

Originally Posted by Starter986

Thank you, Pipe. That Burner vid is one of the vids I watched and recall my horror at the exactly one minute mark... when he begins strong arming out the unit. The closer arrives at 17:42 when after summing up with, "So that's it. That's the whole process" he hits with, "You put everything back in the way it came out".

While I was testing the relays... jumping... running car to temp... etc. I had a constant mental loop of that video and hoping that wasn't the route I would have to take.

Snuck my hand under... fan spins freely.

Tomorrow morning I'll lift that side... peel back the liner... see if I can't access the electrical connection... to which I'll run 12V... without having to take off a bunch of parts.

Have a nice evening.

Yeah, I was horrified, too!

But if you can get to the plug, after you unplug it, jump the terminals at the relay sockets and use a test light to see if you have power at the plug. The plug has 3 pins, two are power (low and high) and one is ground.

You can also try, like you said, running 12 volts to the fan-side plug and see what happens. Keep in mind the black wire is the negative and the other two are where you'd connect positive. If for some reason there's no black wire, it's the only one going directly from the fan motor to the plug.


Here's what you can do if you want to jerry-rig it. (might work if you're in a bind, but not the way I'd do it):
https://www.youtube.com/watch?v=MrD52LDH0WI

Good luck!

[Starter986]

Connected 12v... ground... fan didn't run. From below gave the fan a few taps. The fan runs.

When I applied the hot wire to each of the two prongs (low speed prong/high speed prong) the fan ran only at what seems to be low speed.

So... I plugged the connector back to the fan... started the car... turned on AC... fan was running but not as strong as the passenger side. Checking the passenger side the fan seemed to be running on high. Car was cold start. It seems that the fan motor must have bound up... even though the blades freely I had spun.

From what I understand the resistor serves the low speed side of the fan... and because the fan is on low should I assume the resistor is good?

Since at the cold start the passenger side fan was running high... should I assume that that resistor is bad and defaulting to the high speed? That wouldn't make sense... but I defer.

Should I, with the car parked, run the engine until it reaches operating temperature... see if the driver side fan comes on? Yesterday I did that and after reaching operating temperature the passenger side high speed kicked in... but not the driver side.

I don't yet want to button back up the wheel shroud until I get this sorted. Are there any other tests that I should be performing? Or, do I button it back up and keep an eye on the driver side fan... and leave the passenger side fan running high?

Any input, direction, or guidance is appreciated. Thank you.

[piper6909]

Originally Posted by Starter986

Connected 12v... ground... fan didn't run. From below gave the fan a few taps. The fan runs.

When I applied the hot wire to each of the two prongs (low speed prong/high speed prong) the fan ran only at what seems to be low speed.

So... I plugged the connector back to the fan... started the car... turned on AC... fan was running but not as strong as the passenger side. Checking the passenger side the fan seemed to be running on high. Car was cold start. It seems that the fan motor must have bound up... even though the blades freely I had spun.

From what I understand the resistor serves the low speed side of the fan... and because the fan is on low should I assume the resistor is good?

Since at the cold start the passenger side fan was running high... should I assume that that resistor is bad and defaulting to the high speed? That wouldn't make sense... but I defer.

Should I, with the car parked, run the engine until it reaches operating temperature... see if the driver side fan comes on? Yesterday I did that and after reaching operating temperature the passenger side high speed kicked in... but not the driver side.

I don't yet want to button back up the wheel shroud until I get this sorted. Are there any other tests that I should be performing? Or, do I button it back up and keep an eye on the driver side fan... and leave the passenger side fan running high?

Any input, direction, or guidance is appreciated. Thank you.

Sounds more like your fan motor is on its last leg, especially if it came on after tapping on it. Both sides should run at the same speed, so if the right side is running at high speed and the left is running slower, it doesn't mean that the left is running at low speed. It means that it's running slow at high speed, another indication that the motor is bad.

[Starter986]

Originally Posted by piper6909

Sounds more like your fan motor is on its last leg, especially if it came on after tapping on it. Both sides should run at the same speed, so if the right side is running at high speed and the left is running slower, it doesn't mean that the left is running at low speed. It means that it's running slow at high speed, another indication that the motor is bad.

I believe you to be correct. I did some more reading and find that at low speed the fan virtually is silent. I had to get down there to hear it running. The high speed... that you can hear. I did find that the passanger side fan on low I could hear... and it sounded 'healthy'. The driver side, in comparison, was maybe half the speed and... from the same vantage point... I couldn't hear it until I got under it. That said...

Just came in from doing some more diagnosing. I removed the four relays. I then jumped each of them.

Passenger side high and low speeds relays. Worked.

Driver side relays? Nothing.

Reinstalled the relays... started the car (cold)... turn on AC.

Passenger side fan high speed on.

Driver side fan. Nothing. Reach under... a few taps... starts spining low speed.

It appears that a new fan is in order... you called it..

Couple more questions...

The passenger side coming on high speed. It should be low speed. Does that sound like a resistor? Should I purchase a low mile used resistor... with the entire harness... plugs... swap it out? Should I replace the entire fan unit?

Likewise the driver side fan. Low mileage used... ~$60? New aftermarket ~$65?

WWPD?

[piper6909]

Originally Posted by Starter986

I believe you to be correct. I did some more reading and find that at low speed the fan virtually is silent. I had to get down there to hear it running. The high speed... that you can hear. I did find that the passanger side fan on low I could hear... and it sounded 'healthy'. The driver side, in comparison, was maybe half the speed and... from the same vantage point... I couldn't hear it until I got under it. That said...

Just came in from doing some more diagnosing. I removed the four relays. I then jumped each of them.

Passenger side high and low speeds relays. Worked.

Driver side relays? Nothing.

Reinstalled the relays... started the car (cold)... turn on AC.

Passenger side fan high speed on.

Driver side fan. Nothing. Reach under... a few taps... starts spining low speed.

It appears that a new fan is in order... you called it..

Couple more questions...

The passenger side coming on high speed. It should be low speed. Does that sound like a resistor? Should I purchase a low mile used resistor... with the entire harness... plugs... swap it out? Should I replace the entire fan unit?

Likewise the driver side fan. Low mileage used... ~$60? New aftermarket ~$65?

WWPD?

Are you sure the fans run at low speed with the AC on? IDK for sure, but I expected them to run at high speed. Someone please chime in here to confirm.

Also, I've always had better luck with used, low-mileage OE parts than new aftermarket. If I found a low-mile OE fan for $60, I'd definitely go with it over aftermarket.

[Starter986]

Originally Posted by piper6909

Are you sure the fans run at low speed with the AC on? IDK for sure, but I expected them to run at high speed. Someone please chime in here to confirm.

Also, I've always had better luck with used, low-mileage OE parts than new aftermarket. If I found a low-mile OE fan for $60, I'd definitely go with it over aftermarket.

Everything I've read suggests that the fans run low when the AC is turned on. With the AC off the lows pop on at around 210... the highs kick on a little higher than that.

With my AC on... the left side is running low... and the passenger side is running high.

The other odd part is when I ran a jumper from the top vertical slot in relays 20 and 21... each seperately, and plugged the other end into the horizontal on 18 and 19... nothing. It is only when the 18 and 19 relays are plugged in does the fan work. Odd.

That's the puzzling part.

However, I do know I need to get a couple of fans. Arghhhhh.

Thanks, Pal.

[78F350]

There's way too many words in this thread for me to read, but here's a link and a pic to follow up the PM.
radiator cooling fan resistor values?



I've done this in 2, maybe 3 cars now and no failures after several years.

[piper6909]

Originally Posted by 78F350

There's way too many words in this thread for me to read, but here's a link and a pic to follow up the PM.
radiator cooling fan resistor values?



I've done this in 2, maybe 3 cars now and no failures after several years.

After seeing your very impressive rear quarter replacement on This (or That? I can't remember,) I'm more than a bit surprised you'd use a jerry-rig like that. Yes it works, but.... IDK.... seems like you're inviting electrical/corrosion issues. That's just me.

To each their own.

Besides, I don't think the resistor is his problem since he has to tap on the motor for it to run.

[steved0x]

Originally Posted by Starter986

I jumped all relays... just to be certain.

The driver side high speed fan, when jumped... silence.

Once I get this repaired I'm going to go the switched fan route.

That said...

Watcha think? Do I purchased used, and hopefully from a lower mileage specimen, or do I purchase that aftermarket new one for ~$65?

Thank you.

Sounds like it is the fan (as you had already figured out ) If there isn't a huge price difference I would go with new, but I have never priced them out. Both of my fans are going strong at 154,000 miles so a low mileage used one would probably last for a long time.

Adding the switch I feel really helped me, I used to just turn it on at the end of a session and I could really see the oil temp coming down, so then I got to where I just turned it on at the beginning of every track session.

My 987.2 Cayman, from what I understand, has variable speed fans that are not as easy to jumper them to run on high, so I haven't done that mod yet on the Cayman...

[78F350]

Originally Posted by piper6909

... Yes it works, but.... IDK.... seems like you're inviting electrical/corrosion issues. ...

The .5 Ohm 100 watt resistors work just was well as the stock and have better cooling. I prefer them to ~20 year old used ones and pricing new Porsche ones at over $180 at Pelican makes the choice easy.

Originally Posted by piper6909

Besides, I don't think the resistor is his problem since he has to tap on the motor for it to run.

That does sound like a bad fan. I hadn't read through the discussion about the specifics, but posted here to reply with the pic of the resistors after Starter PMed me a direct question and linked me this thread.

[Starter986]

Originally Posted by steved0x

Sounds like it is the fan (as you had already figured out ) If there isn't a huge price difference I would go with new, but I have never priced them out. Both of my fans are going strong at 154,000 miles so a low mileage used one would probably last for a long time.

Adding the switch I feel really helped me, I used to just turn it on at the end of a session and I could really see the oil temp coming down, so then I got to where I just turned it on at the beginning of every track session.

My 987.2 Cayman, from what I understand, has variable speed fans that are not as easy to jumper them to run on high, so I haven't done that mod yet on the Cayman...

Yeah... I'm leaning towards both fans.

This morning I tackled the driver side fan removal. Hooked it up to 12V... and nothing.

The passenger side fan, because it starts on high speed, is a candidate for replacement.

I found this pair: https://www.carparts.com/details/Porsche/Boxster/Replacement/Cooling_Fan_Assembly/1998/SET-RP16090001-2.html

I've read that aftermarket fans are made of less superior components... and some reports claim vibrating and wobbly. That causes me concern because I won't want to be replacing fans forever.

So I'm leaning to a pair of fans pulled from the same car and, hopefully, with reasonably low miles. Just the fans... connector and resistor attached... plug and play. I'll be posting a WTB ad soon but, in the meantime I welcome any offers for a pair of fans.

Cheers!

[piper6909]

Originally Posted by 78F350

The .5 Ohm 100 watt resistors work just was well as the stock and have better cooling. I prefer them to ~20 year old used ones and pricing new Porsche ones at over $180 at Pelican makes the choice easy.

I totally agree with you on that. And I have no concerns about the resistor itself. Living in the rust belt, I get concerned about corrosion with splices. Even with the best attempts with shrink wrap and all, around here you're just inviting problems. I've seen it.

In your neck of the woods it's totally different environment and most likely not an issue.

[Seal1968]

I bought similar resistors and replaced both of my old heat-soaked and worn out factory ones. (only 1 was malfunctioning)

Total cost was under $20, and 15 minutes installation including soldering and heat shrink. Didn't have to remove the inner fender either, access is easy from underneath.

They do not look like a hack job either, they look like an upgrade. You can search, I posted up my DIY a year or so ago.

BTW...If you're buying 1 new fan, why not do both with all new resistors? Then you don't have to go through this again...and it will likely happen. The factory resistors are prone to failure as they get old, and given their location.

Enjoy!