Getting OAT Coolant residue off Air Con Radiator

[fly fisher]

Hi.
I have Morgan with Air Con, where the air con radiator sits below the engine one.. Now I have a leaking radiator which has dripped OAT coolant all over the Air Con radiator.

What is the best way to remove the OAT coolant residue, I tried water but that doesn’t work and don’t want to damage the air con rad.

Thanks
Will