85 Olds cutluss Cierra electric engine fan problem

My dad's car, a 85 Olds cutluss Cierra has a problem with the electric engine fan. When you turn the car off the fan comes on for about 5 minutes then shuts off even when the engine is cold. It does it every time whether the engine has been running 5 hours or 5 seconds. The temperature gauge is working ok so that means the sending unit is OK? Not sure where to start to find the problem. It always shuts off after 5minutes or so so it's not draining the battery. Not yet anyway.
Thanks for any advice you cn throw my way.

RYoung
or not Hi rene, Actually there are 2 senders...1 for the gage and another for the fan and they work independant of each other. So just because the gage appears to read normal doesn't mean that the fan sender is calabrated correctly. Yours is a problem I haven't heard of before. Caddy had a problem with fan relays sticking on and the fans would run until the battery went dead. But in your situation I would monitor the fans and if they continue to time out then I wouldn't start replaceing any parts. Maybe someone else has experrianced this condition and can enlighten us. Keep us posted. Bill Like Bill says, there are two sensors. In some cases one sensor pulls double duty. So it is possible your gauge reads OK but the computer is still seeing the wrong signal.

The problem is either the sensor or the relay. Both items are relatively inexpensive, in case you want to replace both yourself without further diagnosis. If you do nothing, one of these times the fan will come on and stay on until the battery is drained. Thanks for the input. since the parts are cheap compared to what it will cost to come and rescue the dead car I will just replace relay and the sending unit.

RYoung