woops

 

With your heater control (blend door) turned fully to cold, the core gets blocked off. Air will still pick up a little heat but it shouldn't be very much. Are you sure your blend door is fully functional?

 

When the a/c is turned on the vents blow fairly cold when the temp switch is full left, and pretty hot when fully right so I'm assuming it's working 90-95%. The hot air blowing in through the floor vents is a very slow blow but when I'm battling outside heat and not running the a/c to keep from overheating the engine, it's basically the straw that breaks the camel's back. I was sent the below pic as a solution and I think that's how I'm gonna do it.

 

I like the 4 port ford explorer heater hose valve as it allows coolant flow on heater hoses even when bypassing the heater core
it is vacuum operated

 

Yep that's the ideal valve, functionality wise. I just don't trust anything plastic anymore. They've let me down so many times.

 

GM used vacuum operated shut-off valves too. I believe they went into the 5/8" line. They rigged it so when the AC went on, it shut off the flow to the core.