Mine is 1996 850. I bought it Jan 2004 with tons of problems, and here is the latest headache.
Whenever I drive the car with AC on, the temperature gauge Intermittently drops, and when it drops, the radiator fan won't go off even when the engine is off.
I have read previous posting about similar problem, but mine only happens only when the AC on. Is it the thermostat failure too?? Does this car have water pump to circulate the radiator fluid??
It is a comfortable car, and I like the color (Yellow). But all of the comfort can be ruined by small electrical gauges that shows faulty parts. I might post another problem if this one can be answered.

Help !

Yes, you have a waterpump, it is driven by the timing belt. I would replace the thermostat and the engine coolant temp sensor. They are right there together, and it is the ECT that keeps the fan on. I believe, and I will have to check my book to verify this, when you turn on the AC, it bumps the fan stage up a notch, so that you are cooling the radiator AND the condensor.

Thank you Chrissij .

The reason I questioned the water pump is that the temperature (sometimes) back to normal when driving on freeway, and drops when driving on suburbs or when the traffic is densed.
So the water pump is not visible, hidden inside the timing belt cover.

Sounds like a thermostat not working correctly and etting the coolant circulate all the time. Dropping momentarily could be a symptom of low level of coolant, and the AC is aggrevating this.

Thank you Moregolf, but I prefer moretennis.
The coolant level is steady, but I will take a look at the thermostat.
Do you know if this car uses water pump to circulate the coolant?
Why the radiator fan won't go off when the temperature drops?? doesn't it make the engine even cooler?? which is not good.