Hi folks. My B.O.M.B (Break Out More Benjamins) has started self-switching from dash to floor to defrost while accelerating. Just put out some more Benjamins on it for a fuel pump. The service manager said the venting issue is because of a cracked vacuum "canister". He said it was a cell-phone size 'box' on the driver's side wheel well or at the firewall?

Can anyone direct me to the exact location? And tell me exactly what to call it when I go to the parts store.
Thank you in advance for reading this. I wish you all good health and safety.
Robert

2003 Mercury Grand Marquis GS. It does NOT have an EATC. It is a manual system with a dial for temperature, a fan speed switch, and a mode selector.

 

Problem solved, thanks.

ps --> don't know how to delete it.