Weird HVAC behavior after replacing heater valve

[Juanhmi]

Had a leaky heater control valve a few weeks back, replaced with another Amazon unit. Definitely no longer using coolant, and A/C has been nice and cold, but we’ve had a few cold days in Kentucky and when I’ve gone to turn on the heat, I get ice cold A/C. Looked under the hood, and while the HVAC sknob is switched to any of the heat settings, the heater valve is not “sucked up” by the vacuum line. When I switch the HVAC to off, the valve sucks up, so no vacuum leak. Did I hook up the valve backwards or something?

 

[Fix4Dirt]

wonder is it a blend door that wont seitch from cold to hot? not an AC guru by any means though! going off my vsery little knowledge on it

 

[Juanhmi]

Replaced heater control valve with a new unit. Still no heat coming through. Hot hoses going in and out of the heater core when A/C is on but not when heat is selected. I’ve goofed with the vacuum lines from the selector and have seen the blend door work properly. What the heck!