Re: damm air con.............
The coil connections should be switched - not permanent 12v - I think. The permanent 12v should go to one of the larger connectors that are switched by the coil.
Is the relay mounted in front of the battery (like the 146), if so then check that the wires to the terminals aren't corroded and broken (like my 146).
Also I think there is a pressure switch in the circuit, not sure but I think this stops the system from working if there's no coolant (and no pressure).