E30 Project: Auxillary Fan Install and Chasing Electrical Gremlins

From when I first bought the car, I really wanted to start to dive into the manual swap but there were some glaring issues with this E30 that had to be fixed before I could even drive the car long distances. The two main issues I needed to rectify were the rat’s nest of wiring under the driver-side dash and the auxiliary cooling fan which was manually operated by a switch above the radio. The rat’s nest of wiring appeared to be from a wiring job left half done and the auxiliary fan was replaced with an aftermarket fan with a manual switch instead of using the car’s integrated sensors which kick the fan on when the A/C turned on or when the vehicle needs additional cooling. A lot of automotive detective work was needed to figure out what was chopped up and left undone. I’m not the world’s best electrician but with some applied common sense and research, this job wasn’t too complicated. Unfortunately, from my experience, older cars that are around 30 years old, this is the reality new owners will confront when purchasing a project car. Some of these cars have changed hands so many times and each owner has put their stamp on them, for better or for worse. This might scare people away from projects like these, but I enjoy it. Discovering what is broken and fixing it right is what I love about these project cars. Finding and fixing something is my disease for which there is no cure. 

Switch installed in the car to turn on the Auxiliary Fan
Installed aftermarket fan with complimentary wire nuts

When I was test driving the car, the old owner told me when I ran the A/C or if I got stuck in traffic, I needed to flip a switch above the radio, that turns on the auxiliary fan. This was a huge red flag for me and I knew right then and there, this was wrong and it needed to be fixed properly. First things first, I had to pull out the switch and from above the radio to see what I was dealing with. The switch had three wires, two of which went to the actual fan. As for the fan, I had to take off the front bumper and valence to get at the thing. A lot of this hardware was corroded and will be replaced with stainless steel parts to prevent future corrosion. Once removed, I confirmed what I had suspected. An aftermarket fan was used to replace the OEM fan. The cringiest part of the whole installation was the wire nuts used to wire up the aftermarket fan. Although shocked by the installation, I wasn’t undaunted. This seems like a simple repair. I also discovered some front-end damage. I realized the front valence would need to be replaced, but structurally, the car was fine and it was only superficial damage. My guess was it was just a fender bender on the freeway. I decided I would rip out the switch wiring and replace the aftermarket fan with the proper part. 

Stock auxiliary fan sold on ECS
New Nissen A/C condenser

After a quick trip to RealOEM online, I found the exact part number I needed to replace the fan. The fan wasn’t exactly cheap at $153, but I was scratching my head about why the previous owner would go to such an extent to replace the fan in such a strange way. Why not just spend the money on the correct part and do away with the need for a switch? Buying a switch, running the wire, going through all the labor to remove the valence and bumper, and putting it all back together seemed like a colossal waste of time. I was kind of speechless. It might a been a case of good enough. I will never know the answer, but sometimes I think doing it wrong is even harder than doing it right, at least that was the case for this install. I was also perplexed because the A/C condenser was also replaced with the exact Nissens replacement part for the car. Even though I was confused, the Nissen condenser allowed me to install the fan as it came from the factory. I purchased the fan from ECS but also decided to do it right and install all of the correct hardware. A search on RealOEM and ECS and all of the hardware and fan were purchased.   

Hardware needed to install the auxiliary fan
Hardware needed to install the auxiliary fan

After the parts arrived, The installation was quite easy. The installation included a couple of bolts, washers, and rubber grommets, and everything was installed perfectly. With the switch removed and the fan installed and connected to the factory plug, the fan worked flawlessly. The auxiliary fan kicked on when the A/C was turned on and kicked on when the engine temp got hot. This was a perplexing simple project and quite satisfying. With minimal effort, I essentially returned the car to a stock-functioning condition. This was a feeling I would characterize as righting a wrong. Now it was time to return to the rat’s nest of wiring under the dash.

The new fan clipped into the stock connector
Stock fan hardware installed
Stock fan hardware installed
Stock fan hardware installed

When I purchased the car and test-drove it, the wiring under the dash was an immediate red flag for me. It was obvious something was wrong since the panel covering this location was missing. I am no electrician and chasing electrical gremlins is not what I signed up for. I was hoping this wiring was just untidy and only needed a clean-up. I pulled apart the speaker and discovered the brackets for holding the Central Locking Control unit and Interior Light Timer were completely missing. My gut was telling me someone was in here for some reason and pulled apart this area and then misplaced all the brackets and then just threw it all back together for someone else to deal with. Anyone who has worked on a car project has suffered from lost and misplaced parts so this wasn’t a complete surprise. I also keep telling myself that O bought this car to fix it up and this is exactly what you are doing, so don’t lose faith and get too frustrated.  

Another item that was concerning was a few cut wires. The driver’s side door did not open with a key but did open with the central locking when unlocking the car at the trunk or passenger door. I initially thought this was due to these cut wires, but after some digging, I discovered there was a common issue with the central locking system and soon discovered this was actually intentional. However, it seemed half-done and crudely done. 

State of the wiring under the Driver's side dash
Cut wired under the dash

I decided to tackle the missing brackets first. A quick Google search led me exactly to the brackets. The Central Locking Control Bracket and Interior Light timer brackets were found on eBay for an exorbitant cost of $13. This part of the project was not going to break the bank and was glad to know this was a simple fix. This part of the car is quite fiddly though. After some research, I found that the sunroof drain flows right past these two modules and often if there is any water splashed on these modules, they tend to short out. If the rocker drains get clogged, these two modules are the first victims. I also found a website that recommended filling the wiring connectors with dielectric grease to keep any water out of the modules. After filling up the connectors and securing the modules with the brackets I dove into the cut wires. 

Missing brackets for securing the Central Locking Control Unit and Interior Light Timer

When researching this location I came upon the Library of Alexandria for E30 common issues. RTSAuto.com had an article detailing the exact issue I was dealing with. I also think the person doing the repair before me ran across this article too. The reason for the cut wires is to eliminate a redundant wire loop that goes into the door first and then goes into the Central Locking Control Unit. The article explains its best. “Essentially there is a black/red power wire that runs from the fuse box, down into the driver’s door, makes a loop around, comes back out the driver’s door, then into the central locking unit which then bounces over to the interior light relay. The loop that it does through the door is completely unnecessary. If either of the two red/black connectors in the door fail because of moisture or a fudged barrel pin, that means your central locking will not work.” The previous owner had done a poor job of it and cut the wires and using an insulation displacement connector instead of splicing the wires and covering them with a heat shrink like it should have been done. 

RTSAuto.com article dealing with my cut wires
Schematic showing what wires need to be cut and spliced

Before I locked in this repair, I did my homework. I wanted to ensure I had the exact wire mentioned in the article. I have the Bentley Manual for the E30 and I cross-referenced the wiring diagram. Sure enough, it was there. I also checked on a few forums to identify where the wires were on the door connector. A user had graciously posted where the wires were located. After double-checking the article, I spliced the wires using a crimp connector with heat shrink integrated into it. I could now sleep safely knowing that my car would now not burn to the ground due to an electrical fire behind my driver’s side speaker. This was a huge relief and this put me one step closer to getting toward the manual swap. 

Bentley Manual wiring diagram showing the Central Locking
Location of the Central Locking wires in the door connector

After completing the wiring job, I put all of the wires, speakers, and modules back into place. I am still missing the cover and still haven’t sourced a good replacement but since I am far from completing the final aesthetics it doesn’t bother me too much.  Again, the goal is to get the car running and mechanically safe before I jump into modifications. The fan installation also added to my piece of mind with this car. I still don’t understand why it wasn’t done right in the first place, but alas, I’ll never know. The fan installation went perfectly, but the balancing clips on the did rust and some of the screws holding on the fan brackets were also rusted. It took everything I had to not go down to the hardware store and online and buy stainless screws and clips. I told myself I had other things to address first. Next up, I decided I need to tackle the headlights since only one side was working. The previous owner had installed cheap HID units that had crapped out. Motor on.  

Cleaned up wiring rat's nest
Stock installed auxiliary fan