My 1970's Trane Convector Radiator is stone cold. ?

Our upstairs convector doesn't work. We don't know if there is a TRV, if there is we don't know where it is. We have read many suggestions about radiators on different sites but do not believe any of them apply to our situation, as the solutions do not fit the description of our convector.I don't know what information you would need to assist us in our situation but would appreciate any help you could offer.
It is a Trane convector-radiator. It's the only one in the house that doesn't work. Please help.