I have been looking at the schmatic of the relay in the manual; built into/inside of the relay is a Resistor that acts as a temperature sensor and there is also a timer. I think either of these 2 parts of the relay could also cause the problem you are haveing.
It could also be the ignition switch!
So it looks as if there is no clear choice unless you can borrow a good relay from some one. It needs to be the exact same ralay as the older ones have a temperature sensor that is not inside of the regulator and somwhere on the engine with its own wire.

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84 300D, 82 Volvo 244Gl Diesel