85 300D is stuck at full heat-is the monovalve or "flap" or what stuck? Fuse 14 blows over and over and I can't find the short.

No heat modulation

In order to get rid of heat I was thinking of bypassing my heater core for the summer.

I just want to make sure its not one of those Flaps that is stuck.

Is this condition (Full heat) caused by monovolave or flap setting or other?