i believe its right under the coolant container its the long black box if your fan its not coming on you can check the radiator by the battery side that's the temp switch they go bad too or check the fan belt.
Under the coolant bin, on the right top side of the hood.
starter relay location
There is a Coolant Fan Control Relay on the main relay panel ('98 -5/'03), located under the left side of the instrument panel, Position 13, number on relay, 53, 2nd row, far right.
It's a 30amp fuse for the rad fan motor on a 1994 vw golf 1.8L engine. It's location is #19
rtrt
Dont know about the 98's but if its anything like the mk4's it would be located in the fuse box that sits on top of the battery.
In the thermostat housing
have you checked your coolant temparature sensor
under the dashboard number 167.
On top of the battery
The temperature sender is probably grounded out and keeping it on.
rear window wiper perhaps? That's what it is on a 96 Golf