I just installed a larger CCA battery. When I removed the factory battery, I noticed there was two little hoses connected to the back of the battery tray (one black & one red). The hoses ran up the firewall behind the engine. Any ideas what they're for??

1999 F250 lightduty S/C XLT 4x4
5.4L, 3.73, 4R100 trans.

 

It might be the vacuum reservoir for the A/C & Heat controls. The old trucks had it on the side of the A/C evaporator case, I think I read that it was moved to the battery tray area on the new.