Not fimilar with the placement of the valves on a Forrester, but on my Lexington there is one valve in each of the rear storage compartments, one for each side.
Pretty sure the Forrester is set up the same way.
A few points concerning the air bag set up...
1. The bags are rated for 100 psi maximum, per side.
2. The bags themselves are small, about the size of a 3 lb. coffee can.
3. It does not take any time at all for a compressor to hit 100 psi in each bag.
maybe 15 seconds or so. When adding air, just "blip" air into the bag, a few
seconds at a time. Very easy to go over the max and blow out a bag.
4. Depending on your rear weight, you may want to start off with 50-60 psi in
each bag. I run 70 psi in ours, and most run around that amount.
5. Don't run the bags empty. Try to keep a minimum of 10-20 psi. Empty
bags will rub upon themselves and wear holes in them.
6. Check the bags weekly when using your rig. They will leak down a bit
over time. Not a cause to worry...just the nature of the bags and fittings.
Steve & Cheryl + Zoey, and Ziggy, our furry kids.
2012 Forrest River Lexington 283ts
Toad, 2013 Subaru XV Crosstrek