Hi Trevin,

I figure maybe you were searching the board for http://www.brickboard.com/RWD/index.htm?id=781119 (Tatra Mike's pictures). There's a chance you may be able to postpone the heater valve replacement, as Volvo's air conditioning manual suggests:

With the car warmed up and the heater control fully cold, feel the two pipes at the bulkhead connector just to the right of the foot feed. Take that right kick panel off. One should be cold, but it probably won't be.

Most likely the valve stem in the heater control valve has rotted, but the other time dependent issue is the capillary tube that provides the feedback control. In the first pic, an adjustment can be made to get the wax motor (second image in foreground) to further shut the valve. These wax motors die just like your airbox thermostat. The second photo shows me crudely handling the adjustment with a needle-nosed plier, instead of finding a torx bit for the Chapman tool. It sits in close quarters along the hump.

Of course, your cable could simply be loose. Once you play with the control you'll see how it all works and quickly determine whether the valve is getting the mechanical travel it needs to close. Unfortunately, these valves are getting mighty hard to find, and the replacement offered is a modification kit to install a plastic gate valve with no feedback control you see in the link above.

Diagnose first, order parts later.