190E cooling fans run all the time! help.

[bungy151]

I have a prolem with my cooling fans for my 1991 190E 8v.
The fans ( both the magnetic clutch cooling fan and the electric fan for the a/c) are always on, even at start up when the engine is cold. The problem seems to be with the dual contact relay that when energised brings on both the cooling fans. It used to be that when the a/c was turned on, both fans would roar into operation, but now they both are on even when the a/c is off. I think it is a sensor or short in the wiring?
I have checked the operation when they are on and i pulled off the plug to the 100 degree C temp switch just behind the thermostat, and that did not stop them. I assume that this switch is ok. The only way to stop them was to pull the connector that goes to the a/c drier I think it is high side pressure switch, the one with the pigtails and white connectors. But I don't know why this is in cicuit with the a/c off?
I know that the electric fan for the a/c has 2 speeds and that there is a resistor near the headlight that gives the low speed it checked out ok, .4 ohms and no hot joints. Would there be a problem with the a/c pressure switch or the a/c relay. Some insight into the fan's operation would be appreciated.
David.