No. It is the evaporative emissions service port (funny, that's what it says on the tag).
Look on the side of the accumulator can, on the firewall, under a ton of crap for the low side port.
If your original owner's manual is missing, download a soft copy from www.fleet.ford.com
under the PARTS AND SERVICE tab.
1995 Mustang GT Convertible, only 68K miles. 2000 Ford Contour Daily driver.
2001 F250 SD, 6.8L, 4 X4. 2007 Mercury Mariner AWD - Wifey's daily driver,
Timesert 5553 kit available for rent, PM me.