May be Very Difficult to Access
We don't have a 34' but ours are very difficults to find. In addition, they don't look like the picture shown in our manual.
Assuming they are located where the manual (an maybe where the PO noted) be sure to look under/below any wiring, ducting, other hoses, etc. I can just barely get my hand into the cubby, under the wires, under the duct before I finally get just my finger tips on the valve. It's an ordeal to say the least. Now that I've done it a few times it's not nearly as difficult as the first time. I bet I spent the better part of half day searching for them the first time. They really are the low point in the plumbing system.
Lucius and Danielle
1992 29' Excella Classic
1996 GMC Suburban C2500 7.4L
2005 Chevrolet Suburban K2500 8.1L
Got a cooped-up feeling, gotta get out of town, got those Airstream campin' blues...