So i have a 2002 ford ranger 2.3l 5 spd. Other day i noticed i had a hose leaking so i fixed it and in the process i broke the hose connector block up by the blower motor(not exactly sure what its called but the 2 lines from the heater core run into it and then run out the bottom side and theres a vacuum operated valve inside it) so i bypassed that, at this point the heat still worked great. I also noticed the thermostat housing was broke/leaking, so i replaced it tonight and now i have no heat, Im assuming the thermostat is stuck closed? Is the thermostat told to open/close from the little sensor thats on the housing or is it mechanically controled by the heat from the coolant?

What does that little block by the blower motor do?
What is the sensor for on the side of the T-stat housing?
Thanks!!
Rob