My 1999 plymouth voyager van's radiator fan constantly on

There is a fan relay in the fuse box in the engine compartment. Usually that is the reason why it won't turn off. It fuses in the on position. If you have the manual it will say which one is the fan relay. just pull it out and get a new one. They are not expensive.

Hope this helps

The fan on this van is electric and heat activated. It will run when the thermostat shows the tempurature is too high regardless of whether or not the engine is on.

If it is working correctly it should turn off in no more than 10 minutes assuming the engine weren't actually overheating.

If it is staying on longer than that, the fan's thermostat may need to be replaced.

If the fan comes on when the engine is cold, then you can be pretty sure the thermostat is the culprit.

I hope this helps.