Heater Core

[Action]

This may sound silly, but which line supplies the heater core with water? The one coming from the crossover? Or the line coming from the water pump?

I ask because I think my core is getting warm or hot and bringing my a/c temp up. I may be due for a new electric water valve. It looks to be closing all the way, but the hose between the valve and the firewall gets quite warm or hot. I may just bypass it until it gets a bit cooler outside.
On the passenger side of my m1152 dash duct, the difference in vent temp between those two vents is at least 10 degrees, I installed the new style driver floor vent and temporarily sealed off the old duct (next to evaporator) with towels and tape.

Jason

[Action]

with engine at operating temp, truck in shade, 88 ambient, 52% humidity, "feels like" 93.

rubber hose between water valve and firewall is 153.
stainless tube right below it is 113
the exposed lower left corner of the heater core (inside) IS 73.

furthest left dash vent is 43
while furthest left dash vent is 57

I wonder if the water in the top of the heater core is getting hotter. I cant feel the rest of the core by hand, unless I remove the dash duct.

Jason

[dilvoy]

The crossover has hot engine water with pressure so that nipple has the hottest coolant as does the thermostat. The nipple on the water pump has suction.

[Action]

Update. I temporarily bypassed the heater core. It gets very cold inside the cab now. My electric water valve was not closing all the way. Even with the piston removed, it will not close all the way. I think it is safe to assume that it is supposed to.
The cold air through the evap was warming up when passing the heater core. I also realized that with the heater core not hooked up, i can open cowl vent and blow fresh air through the ducts. It was either heat or a/c if you turn the fan on.

Jason