I think this might be a tough one. Need some diagnostic wizards to pipe in. My 1996 2.0 TS spider with A/C has one fan. It does the following:
1. On a coolish day, constant driving with no stop and go, the temp rarely goes above 90 degrees
2. On a warm day or when the car is standing idle, the temperature rises. But here's the catch. At idle, it will hit 90 degrees and the fan will turn on to bring it below 90. The fan then shuts off, and the temperature rises again. Only this time, the fan does not turn back on when 90 degrees is hit. The temperature just keeps rising to 100 degrees or more. I'm sure it would just keep going if I didn't shut the engine off.