Cooling fan issues - 986 Forum - The Community for Porsche Boxster & Cayman Owners

mikesz · 08-16-2013, 10:39 AM

The cooling fans on my 99 Boxster are not working properly. I removed the 4 relays and got a jumper between the 87 & 30 connectors neither fan worked at low speed. the left, drivers side, worked at high speed. The right did not work at high speed and keeps blowing fuses when "jump" high speed. So at the very least sounds like I need a new resistor for the left fan. is there any way to be sure? What should I do about the right fan? I was going to remove the bumper to clean between the radiator and condenser. Has anyone replaced a radiator fan? How difficult is it?

rem503 · 08-16-2013, 11:13 AM

MikeSZ,
I removed the fans on my 2000 base. It is a bit of work but not too bad. Removing the diagonal support rod took some effort to remove and put back in place and removing the C clip from the tip of the plastic shroud which covers the fans were the most difficult parts in my opinion.

With the bumper removed for cleaning, you will have better access.

thom4782 · 08-16-2013, 01:25 PM

If the fan works at high speed after jumping but not at low, the odds are really high the problem is the ballast resistor.

Did you try jumping with the AC on? Fans run at low speed with the AC on regardless of coolant temp. I haven't looked at a wiring diagram to see if jumping bypasses the temperature trigger.

AKnowles · 08-16-2013, 01:33 PM

When I went to repalce the ballast resistor on my driver side fan, I didn't know you could just clip the existing wires. Or rather I should say, I didn't know where to clip the existing wires. In any case, I went through the trouble of removing the entire fan housing just so I could trace the wires. The bottom line: it really is not a difficult job.

A couple of things to do ...

1) Jack up the front end.
2) Remove the wheel liner. Buy a couple of repalcement plastic inserts just in case you damage one. Or one or more are missing.
3) Removing the diaganol support requires a bit of leverage/force. When you go to repalce it be sure to put the top part of the strut in first and work the nut on a few threads to keep it in place. That'll help a lot to prevent it from popping out as you work on getting the lower end in place.

The good news is that when you buy a replacement fan, it includes a new ballast resistor so you'll not need to pay for it as well.

The quick and simple way to test the fans is with a PST2/PWIS ot Durametric cable. You can choose low or high speed test settings. If you don't have one, the alterante method is to starty the car when it is cold. Turn on the AC. The fans should both run at low speed. When the car is hot enough and the AC ir sunning the fans should both run at high speed. I forget the actual pressure requirement for the AC refrigerent, but it is listed on the forum and a search will pull it up. Out here, I don't have to worry about it, just turning n the AC and driving and I know it reach its peak value. It's 100+ out here.

thom4782 · 08-16-2013, 01:55 PM

Both my ballast resistors were broken. Because I knew both fans worked on high speed, I replaced the resistors by splicing them in place of the old wires. I mention this because you'll want to clip the old wires near the old ballasts. The make sure you leave enough on the news resistor wires so you can easily splice in the wire connectors. Hope this helps. BTW: I didn't need to remove any fan or bracket parts to do this - just the fender liner.

Brockmeister · 08-16-2013, 03:29 PM

I just did this job last week. Read up on it beforehand. Took 45 minutes. My left fan wouldn't kick on regardless of what I did. Works great now.

trimer · 08-16-2013, 03:55 PM

Quote:

Originally Posted by mikesz

The cooling fans on my 99 Boxster are not working properly. I removed the 4 relays and got a jumper between the 87 & 30 connectors neither fan worked at low speed. the left, drivers side, worked at high speed. The right did not work at high speed and keeps blowing fuses when "jump" high speed. So at the very least sounds like I need a new resistor for the left fan. is there any way to be sure? What should I do about the right fan? I was going to remove the bumper to clean between the radiator and condenser. Has anyone replaced a radiator fan? How difficult is it?

How did you know they weren't working?

mikesz · 08-16-2013, 06:09 PM

Hi All, thanks for the replies.

@Trimer, I could hear the left fan at high speed but did not hear the right at high speed. At low speed didn't hear anything either side and went out to the front to listen and feel if there was any air flowing and there was not. But will try again now that I have the bumper off.

@thom4782. I will put A/C on and see if the low speed fans turn on. Should be easier to tell now that bumper is off.

@AKnowles. I have a Durametric and could not find the cooling fan test. I could only find the engine bay fan test.

@Brockmeister, did you replace the ballast resistor or fans?

thom4782 · 08-16-2013, 06:20 PM

The fans are in the Engine module under activations. Stage 1 is low speed and stage 2 is high speed. You'll see Start and Stop next to each. Make sure to select the DME for your car when opening up the Durametric program so you can see the Engine menu.

san rensho · 08-17-2013, 05:23 AM

A heads up. The ballast is about $110 And the entire fan/ ballast assembly is around $160 from parts geek, so it makes sense to replace everything, although there is bit more work involved.

spongebob · 08-17-2013, 05:37 AM

Any ideas how to wire the relay so that it can be controlled by an OEM switch on the dashboard?
I have no need for the AC most of the year but the continuous running of the fans in low speed always keeps the temperature close to what is possible with a low temp stat.
Or can the trigger point be adjusted by a software update?

mikesz · 08-17-2013, 03:57 PM

@san rensho, yes thanks I did think of that. Just need to figure out how much work to remove the fan assembly. any ideas?

san rensho · 08-17-2013, 05:37 PM

Quote:

Originally Posted by mikesz

@san rensho, yes thanks I did think of that. Just need to figure out how much work to remove the fan assembly. any ideas?

Pedro's site a has good write up. There a couple of fiddly fasteners that are hard to get to, but the biggest problem I had was the orientation of the spoiler, and wheel arch plastic. Be sure you know how they go together, otherwise, its a bit of a jigsaw puzzle to put it bac together. Just remember/ photograph how it comes apart and you should be ok.

mikesz · 08-26-2013, 05:32 PM

thanks everyone for your help, greatly appreciated! checked out the diy on pedro site to remove fan. passenger side wasn't working at all. replaced with one from a parts car. wasn't that difficult just wish I had a lift, I did it in my driveway on my hands and knees. My back was killing me. Now I have to replace the resister on the drivers side and I should be good to go. this will also solve my fuses from blowing too. I need to get the durametric and see if the engine compartment fan is working.