bruce7

In this post I describe how to check and change the AC & Oil fan series resistors. There are many postings on this forum and elsewhere that address this procedure, but what I hope to do is to edit down the subject matter to something more concise and manageable and yet add to the existing information with the aid of photos and a specific materials and tools list that will give you all the info you need to perform this DIY before you start.

Special acknowledgements to pcarworkshop and Tore Bergvill and the many RL forum members that have contributed to this subject.

Part 1 describes how to check the series resistors. (Part 1 photos)

Part 2 describes how to change the AC fan series resistor. (Part 2 photos)

Part 3 describes how to change the Oil fan series resistor. (Part 3 photos)

-bruce

element

I just replaced mine a few months ago.. its tight on the AC fan side, but with the right wrench it is doable.

I didn't use any thermal compound.. hope it has good heat transfer.

phil.

bruce7

Hi Phil,

I checked the access for the wrench prior to removing the lower front part
and although it might be possible (with great patience and frustration) I think it's just so much easier to pull the fan assembly out.

Here is a shot with the wrench. Unfastening is easy, getting it back on is harder due to the cooling plate. Need a 72-tooth wrench here.


Using the thermal compound is completely optional. As far as I know there are no test results published that show how much if any it would help in an auto application. For CPUs and heatsinks in home and office computers, thermal compound can lower the CPU temperature 2-12 degrees C. I spoke to an Arctic Silver application engineer (who recommended the Ceramique 2 product) and told me how to tint the pieces. He said they have never tested it in a car environment. I thought it might be worth a try.

-bruce

EckFe1

Hello Bruce,
What an awesome diy. I do all the work on my car myself, with the exception of a few things and I have posted some improvements I did here on Rennlist as well but never as detailed as you have.
You really took your time and made it as easy as possible for everybody to follow.


Ed

helmet993

I replaced the a/c ballast resistor without removing the fan...took about 20 minutes to do the whole thing including removing the wheel and liner.

bruce7

Good job! I had trouble getting the screw started so that's why I lowered the fan.
Originally I was trying to hold the cooling plate and resistor together so that the
notch did not rotate. I was unaware at that point that the notch does not matter
on this side like it does on the oil fan side. So it's ok to let it rotate while trying
to get the screw started.

This was the first time I did this, but I think if I have to do it again I would try it
without lowering the fan and using a rachet spinner (which I had but didn't think
about at the time). With the rachet spinner you can get more rotation on the screw
to help get it started than with the rachet handle and it's easier to turn than the small
socket bit by itself.

Here's a shot of what I'm referring to.

-bruce

frankv

A question on the testing as described in Part 1.

When doing the low speed test should the engine be warm with the gauge having pointed at 9:00? I understand that the test is done with the engine off. My problem is that in all the time I have had the car the gauge has really only hit the 9:00 when I am stuck in traffic lineups on hot days (not an ideal time to do a test) and for the most part is quite happy at 8:00. When I do the test the fan does not run at low speed. I do feel the front fender is warm. Maybe I shouldn't worry about a problem that I don't have :-(

Thanks, Frank

bruce7

Which test did you do? If you used the jumper wire to do the low-speed test
for the oil fan series resistor and the fan does not run then most likely the series
resistor has failed.

-bruce

gaby1088

This thread should be stickied

frankv

Bruce, I did the low speed test.

What I was trying to ask is "will the fan run by using the jumper wire on the low speed test IF the engine is cold?" Your answer says that yes it should. Thanks, that is what I wanted to know.

Regards, Frank

P-daddy

Bruce,
Great write-up. Your step by step direction with photos are very easy to follow. I agree this should be stickied. Thanks

helmet993

I did use some Hyundai bran sealant between the resistor and plate. That kept it from rotating.

ble2011

This thread is awesome - Thanks.

IXLR8

Hi Bruce,

I'm just in the process of replacing my A/C Fan Series Resistor and going through Part 2 of your DIY, I came across the following: "There is no need to apply thermal compound to the side of the cooling plate that will attach to the cooling assembly air guide".

By that do you mean you did not apply compound between the metal disc under the series resistor and the metal frame the condenser sits in? Why not? Isn't the idea to transfer heat to a heat sink which is what that metal condenser frame acts as.

BTW, removed and installed the series resistor with everything in place as shown in this thread. Tedious but very doable. I even ran a tap through the existing threads to clean them up of any corrosion/dirt. That was tricky.

Next, the oil cooler series resistor. Both were gone.

lopro

both mine needed to be replaced aswell. Nice to have the fans working at both speeds as Porsche intended