Dateline - February 9-10, 2013 - This was a very productive weekend on the car. I had an event planned for the afternoon on Saturday (Chinese Lunar New Year at the Seattle International District), so I knew that I only had a limited amount of time to work on the car, so I decided to figure out where to put the blower fans' speed control resisters.
I have a couple of problems caused by my remodel. The fan speed switch that I'm putting in the car has four positions, Low, Medium 1, Medium 2 and High, while the stock car only has three speeds. Also, the car has two fans, one on each side (I'm sure they did that so that the car would be balanced :) while the blower control I'm putting in the car was only designed for one fan. I wasn't comfortable putting twice the current through that switch.
The speed of each fan is controlled through speed control resisters, located in the engine compartment. Each fan has its own set of resistors. When the fan switch is put to low, the current flows through the low and medium speed resisters in series. When the switch is turned to medium, the current flows only through the medium speed resister. When set to high no resisters are used.
So, I could have used the original resisters and just left one of the fan speeds (probably Medium 1) the same as the Low speed, but the prior owner told me he had problems with the fans running all the time, even after the key was turned off. I suspected a short someplace, and the control resisters would be the prime suspect. So I opted to buy two of the speed resisters that are used in the Chevy Astro that I sourced the control switch from. The challenge there is that the resisters need to sit in the airflow of the fan because they get pretty hot! This means that I had to figure out where I could mount the resisters.
First I wanted to see if the fans actually worked with the new resisters. I pulled out the driver side fan (easily accessible from the engine bay) and using my new power supply I was able to try out each setting and sure enough, the fan worked as advertised!
Then I started looking at places to mount the resister pack and noticed that there are two holes in the air box that were originally used for the A/C plumbing. These holes were perfect! Each are in the airflow upstream of the fan, so they will get the cold air coming from outside, plus the holes are on the inside of the car, so I don't need to cut into the firewall! When I had the air box out last year, I covered the holes with aluminum ducking tape. All I had to do was remove the tape, cut the fiberglass so the holes are the right size and screw the resisters down! A happy accident! Believe me, one of the few thus far!
So, since I had a good idea how I was going to solve the problem, and since I was working in the engine bay anyway, I decided to spend the rest of the day stripping the firewall and fenders for painting. I took out the right side fan (and tested it), removed the fan control resisters, the master power solenoid, the heater water control valve, front and back brake lines, +12 volt cables, ground cables, horn, horn relay, ballast resister, Lucas control module and all the little clips, Adel clamps and screws still stuck to the car. Now all I need to do is scrape the rust, vacuum, clean away 42 years of grease/oil and dirt, prime with rust encapsulator and paint!
On Sunday, I sat down and figured out the wiring for the fans. Like I said above, with two fans twice the current load would need to go through a switch only meant for one fan. I was not happy with that, so I decided to run each speed through a solenoid to isolate the current. I would only need three solenoids because the heater control resister unit already had one installed for high speed. It was a pretty easy process of adding three more solenoids to the nice relay frame I built a couple of weeks back. All I really needed to do was the wiring harness. I put together the six wires that needed to run to each of the control units, wrapped them nicely in electrical tape, and installed it into the car. Nice and clean! It took a lot of time but nothing technically hallenging.
I was also able to use the original wiring to run the fans. I was able to use the plug that originally went to the center console for the +12 hot from the fuse box, and since there are two separate power wires running through the firewall, Green/Yellow and Green/Gray, I was able to run the hot from the fan resister on the left side to Green/Yellow and the right side to Green/Gray. So I didn't even need to run new wires to the fans!
Finally, I took my power supply and an ohm meter and tested all the relays. Everything works great.
I still have to screw in the fan resisters and finish the right side resister wiring and the wiring to the control unit (I ran out of female pins), but basically, my fans are done.
This is a big load off my mind because it was one of the last things I was really worried about in this installation. Everything else is pretty much just an easy retrofit. Knock on wood!
Next week, wiring the cruse control.
