Warm/hot air from the vents all the time: CHECK
Bought a heater core bypass valve to correct the problem: CHECK
Asked SMBw to install it: CHECK
Heater core bypass installed: NOT
When I dropped off my SMB to have some work done at SMBw, I asked them to install the heater core bypass valve. They apparently call the manufacturer but they were out on vacation. So, they called their connection at the local Ford dealership, and they told SMBw that it wasn't necessary, as it was something that had been corrected at some point in the build cycle (don't recall the model year, but mine was supposedly after this date).
Still have warm/hot air from vents all the time: CHECK
Here's the porduct and the site I bought it from (they developed this valve). I never did check back with them to verify what SMBw relayed to me, but I know I still have the constant warm/hot air unless the AC is on. I still have the valve, uninstalled, sitting in a box in my SMB.
http://www.dieselsite.com/index.asp?Pag ... ProdID=473
This disclaimer is on their site, but I'm not aware of this function on my van.
*There are a few 6.0L equipped models with an optional ATC (Air Temperature Control) system. These trucks do not need this modification. To know if your truck is equipped with this feature, look at the upper heater hose on the passenger side of the engine and look for a valve similar to the one pictured above.