I have an '89 2.0Si (not 4WS) that's doing the same thing. The fans will arbitratily come on, even if the car hasn't been running. Keeps draining the battery.
Have you actually tested your relays? On the 3rd Gen, you can test the relays like this:
1. Find pins 2 and 4. They'll be on the right-hand side of the relay (as you're looking directly at the pins) if the front of the relay (the "bump", not the flat part, the flat part will be at the bottom) is facing up.
2. Energize the relay by putting 12 VDC across pins 2 and 4. If you hear a click, proceed to step 3.
3. While pins 2 & 4 are energized, you should have continuity between pins 1 and 3.
If you don't hear a click when you energize pins 2 and 4, your relay is probably bad.
Make sure you test all your sensors, too. I use the "boiling water" method. Take the sensor, and place it in boiling water so that the part that electrically connects to the car is facing up (not underwater). Once the water reaches 190-195 degrees F, the sensor should produce continuity when checked with an ohm meter (on a digital, it will read 0.00). If you get continuity, pull the sensor out of the water and let it cool down. Once the sensor gets below 190 degrees F, if you ohm it out you will get resistance (not continuity). The digital meter I use shows 1.318, other meters may show differently. The thing to note is that continuity should always read 0.00. Some meters might show the infinity symbol, most digital multimeters will simply read 0.00 to indicate continuity.
While you're at it, check out my post with the same problem:
Cooling fan drains battery
If you have any ideas after reading the troubleshooting steps I've already taken, I'd appreciate it.