I have a Williamson Temp-0-Matic unit in my basement.

On the side, there is a Williamson plate with the model number 7124-04-2003 on it. Can anyone advise what year my unit was made and what those numbers stand for, if anything?

Thanks, I am not an HVAC professional, but we have been having trouble with our unit all spring/summer and I'm trying to learn some basics so I don't look like a complete fool when I try to talk to our service man.