Laker

So as I was tinkering/adjusting the low-tone horn, I noticed the oil cooler ballast resistor on top of the oil cooler. Replacing it was on my to-do list since my car is totally original. I've read lots of threads about what a PITA it is to replace, and involves lowering the oil cooler after removing the headlight to get at a bolt. I was able to get my hand on the resistor by reaching from behind with the front mud cover removed. I was expecting the same 4mm allen screw to be used as the A/C resistor, but was disheartened when (using a mirror) I saw it was bolted on. It was bolted on to an aluminum cowl which I assume is there to keep a tight fit between the oil cooler and the body for forced air flow from the front grille. Upon closer examination, the upper cowl was bolted to the body by (3) 9mm plastic bolts. I got them off in about 10 minutes, the middle one is a pain due to lack of space to swing a ratchet.

The front of the car was resprayed by the PO. There is a stalactite of dried paint dripping from the bolt on the fender support cross bar, which made it impossible to remove. (2nd and 3rd picture) I did not have the time to grind/cut the extra paint away. If I had the time, it would have given me more room to get at the plastic 9mm nuts.

I tried to remove the upper cowl, but it wouldn't budge/flex. There is another vertical cowl (already removed on the first two pictures) that is attached to the cooler itself by (3) 5.5 mm screws. It was preventing the upper one from moving.

I cheated and used a 7/32" socket on the 5.5mm screws. Once I removed the vertical aluminum cowl the upper one dipped and came right off.
With the the upper one out, replacement was a 2 minute job with a 10mm bolt. Total time about 45 minutes (an hour if you have to remove and replace the front mud guard.

The yellow circles are bolt/screw locations, green is the wire clip, and light blue is the actual resistor. The 3rd upper 9mm plastic bolt is not in view but behind the wire clip and just to the left of the resistor.
The last photo shows the new resistor bolted to the upper cowl, and the inset on the lower right is the 10mm nut on the other (bottom) side.

mike9186

I just used this approach to change my oil fan resistor and it worked like a champ! It is still not what I'd call a fun job but this post makes it a lot easier.

Thanks!

CoastRider

nice post....Thanks

Rocket Rob

Laker - Great post. I suggest you also post this in the 964 DIY section.

Laker

thanks for the kind word, it's already there:
https://rennlist.com/forums/964-1989...procedure.html

Kuchar

In my 964 I have to replace the resistor placed in the A/C cooler.
And now I have some thoughts ...
1. It is difficult to remove the old - it costs a lot of work
2. And some 964 owners place new resistor in other place than the old.
Q: So what is the reason to remove the old resistor, if we are going to put new one in a different place?

Vandit

I'll be doing this soon since I noticed my fan is only running at high speed once the car's temp starts creep towards 10 o'clock.

I'll likely remove the front bumper since I have some RS ducts I also need to install.

wedion13

it worked like a champ!

Laker

1) It is a lot more difficult to remove the traditional way.
--->remove headlight, remove screw holding on oil cooler, remove bumper, drop oil cooler

This approach,
remove front mud guards, remove vertical aluminum cowl, remove aluminum horizontal cowl and replace.

2) AFAIK this is on the other side for the A/C cooler since the battery vent line discharges right above the stock location.

Kuchar

Today i have " replaced " a/c resistor, but i put new one litle bit above old one.
I use the same hole where was the front hood service openning.
I wonder if it will work correct. Now i have low speed, but i have to wait for fast speed. Tomorrow in Warsaw is 31deg. so a/c will work for good. And i will check.

Silvertarga

Laker, you should win a prize for this one..been dreading this job (the old method) and thanks to you I was able to do this in the 90 degree plus heat we are having today without a hitch, hopefully my ten oclock readings on temp will be gone ...


This shall be known as the Laker Method..

-nick

I was at first cursing Laker's obviously under-developed tiny girly hands when I looked down into this area. But this actually works despite it not looking possible. Tiny hands not even required.

Thumbs-up on this.

And by the way, the failure mode for my '91 was that the oil cooler fan will not come on at all when the resistor goes open. I jumpered the relay and got nothing on the hi/lo circuits. I cut and bridged the old resistor wires and the jumpered relay turns the fan on as it should. Now I'm just waiting for my replacement resistor to arrive.

Laker

Well actually, I neglected to mention, that I just took the pictures. I had some help with the actual resistor replacement and write-up

bo11

i just change my ballast resitor using this method.
The 2 further plastic screws a quite difficult to remove. There is no space to use a wrench. Instead I use a "flexible" wrench (look like a screw driver) in 9 mm (which is the size of the plastic screw) and i remove the screw quite easely. (i will post a picture later on of the tool)

Total timing approx one hour including the wheel arch removal.

This aproach is perfect thanks laker.

YaHoo!

Just pulled this off - worked great and was easy! Thx Laker!