Buzzing sound from Relay

I'm reinstalling the A/C in my 89 grad. After finding out the compressor clutch was kaput, I replaced the A/C Compressor. I've also replaced the receiver/drier and all of the HNBR O-rings. With the new compressor in place and the compressor clutch wire disconnected I turned on the switch to see of the blower motor and condenser fan were still working. They are but the 2"x2" black control box mounted on the back of the air duct work is buzzing like a pissed of bumblebee. Normally a buzzing relay isn't a good thing. I have no idea what it means in this scenario.

I've searched for the control box using the model number. The only listing on the interweb is on the ABB in 2010. There was no response. The little relay itself is available from numerous electronics supply houses on line. But I don't know if that will fix the issue. Help. My wife and start a road trip up through Montana and into Canada next Friday. We want to take the Alfa.
That requires A/C.

Herb