Benefits and Drawbacks
Using an electric fan has many benefits. It makes you car much quieter to drive, removing the “woosh” sound during accelleration which can be compared to that of a UPS truck. The mechanical fan also steals some (arguably negligable) amount of horsepower from the engine. It also slows the rise and fall of engine RPMs, which is the biggest difference you will probably notice – the RPMs drop much faster when you put the clutch in because the electric fan doesn’t create ‘drag’ like a mechanical fan.
However, the stock fan does have benefits as well. It is reliable, effective, and cheap to replace. It is pretty much always pulling air through the radiator/intercooler/air conditioning condenser sandwich. An electric fan is only on when the temperature gets hot enough to kick it on.
I installed an electric fan on my 242 Turbo for basically one reason: when I intercooled the car, I couldn’t make the original mechanical fan line up properly for some reason. I replaced the motor mounts, and double-checked everything, but it just wouldn’t have been centered in the middle of the radiator/intercooler sandwich. In retrospect, I am really glad that I did go to the trouble of switching to an e-fan.
Many people manage to find fans cheaply at junkyards out of other cars, including both Volvo and non-Volvo autos. As long as the fan is 16 inches in diameter, it can generally be made to fit a Volvo application.
However, while inexpensive, junk-yard fans have so many drawbacks that I must advise against them. They are of unknown quality and mileage, and may break down soon after buying them. The last thing you want is for your cooling fan to stop working. Junk-yard fans also are harder to fit onto the car and may require custom fabrication. Another important problem is that they will draw an unknown amount of amperage. Usually, a junk-yard fan draws far more amps than an aftermarket fan. This is very important for managing your car’s electrical system.
I chose a Permacool High-Performance 16″ fan that I purchased through Summit Racing. It was about $100. I chose this fan because it was thin in size (so it would not interfere with my pullys and belts) and because it moved a large amount of air with a very low amperage power draw (only 9.8 amps).
Volvo 240 Turbo’s have a 55 amp alternator stock. Unless your electric fan draws less than 10 amps or so, you are probably going to need an alternator upgrade (70a, 90a, or 110a) to be able to still keep your battery charged while running your fan and headlights at the same time, especially if you install one of those 30 or 40 amp fans.
Wiring the Fan
Getting the fan wired in is probably the most difficult part of the job. The fan needs a relay to be safely operated. A relay basically lets you control (turn on/off) a high-amp circuit through manipulating a low-amp circuit. In this case, the high amp circuit would power the actual fan, and the low-amp circuit would be the switch that turns the fan on and off. Since the fan I picked drew less than 10 amps, I just used a relay that I found on a 240 at a junkyard.
The relay I got was a typical 5-terminal relay rated for 30 amps. It has five male spade connectors on it, labeled 85, 86, 87, 87a, and 30. An expanation of how this type of relay works can be found here.
Here’s the wiring diagram that I used. I ran this by several people and made many changes. This is the final version, and is just about the safest way to set up an electric fan that I could figure out. The fan can be operated manually by a switch, and will also go on at a specific temperature with a thermoswitch. I have my thermoswitch mounted in the radiator, but the upper radiator hose is another viable option.
This step is going to depend a lot on what fan you choose. If you choose some junkyard piece of crap, you’re going to have to determine which way you want it to spin to pull air properly. If you wire it backwards, it will spin the opposite direction that it was designed to and not move very much air at all. But let’s assume you bought a nice new fan because you really care about your car.
Most new fans come with instructions so read them, but basically there are two ways to mount the fan. You can tie it through the radiator with zip ties like I did, but this is not really the best method. Why? Because over time, the bouncing of the car will eventually create holes in the radiator that look like crap if you ever take the fan off. Anway, I chose to set it up like that because my radiator was old and I wasn’t really able to manufacture a custom mounting set up very easily. I just strapped the fan on really tight to minimize jiggling and hoped for the best.
The other option is to rig up some custom mounting brackets. You can make them out of “plumbers tape” which is basically metal strips with holes in them, but this will most likely be too flexible. The best option is to get some sheet aluminum stock or aluminum bars and bend/cut/drill until you have some nice mounting brackets. This can be a lot of work, but if you do any off-road driving or drive over a lot of speed bumps every day, it’s worth it.
The Permacool fan that I chose can be used without a fan shroud, but I chose to modify a intercooler-style fan shroud to protect my fingers and for a more professional / stock look. The fan shroud I used can be found on 1983-1985 Volvo 240 Turbo’s. The non-turbo fan shroud can be used, but if you have an intercooler it will be too large and need some cutting. All I did to modify the intercooler fan shroud was to cut a little bit of plastic out of the inside to give the fan some room to spin. Not very much work at all really.
After a lot of wiring and fiddleing with different things, I got it set up. Before you go on a test drive, make sure the fan is spinning the right way. The instructions I got with my fan had a typographical error that caused me to wire the fan in backwards, making it spin the opposite direction. I went on a drive and almost overheated my car because the fan wasn’t doing anything. A good way to test it in the garage is to use a piece of string or ribbon in front of the grill. If the fan pulls the ribbon towards the radiator strongly, it probably is pulling plenty of air.
Relay intalled (‘below’ the coil in the picture, clipped to the ignition module mounting bracket.)