I have NOS Heater Valve GM 2250236 for an Olds 307 V8 and it has a small female threaded connector on top that my blown original doesn't have. This is the replacement valve listed in the original part book. What goes on that connector. I know the heater hose goes on the big port and the vacuum line goes on the vacuum port but what goes on the threaded female?
It threads into an NPT port at the back of the intake manifold. The nipple goes to one of the nipples on the heater core. The small female port may be for a temperature sensor for automatic climate control. You're probably OK with plugging it.
Apparently they consolidated valve types and that port is only used if you have auto CAC. Nothing attaches to it on mine and the system works fine now that it is installed and no more coolant leak.
