Heater Not so Hot / Consistent

[Rich72C10]

Resolved on Post #25


I read a few older threads on this but thought I'd start my own.

My heater can get warm, though I wouldn't say hot. Then as I am driving it can actually be cool to ever so slightly warm.

72 C10 with 2 Port Vacuum control 4 Seasons - Heater is Stock

1. Vacuum controls are tested as good, Inside door closed tight and cowl opens in Heat mode (for the record the reverse in AC mode perfectly).
2. No Vacuum to AC Type Vacuum Water valve in Heat mode- I do have a manual cut off valve inline, before the Vacuum Water valve for summer time and it is fully opened.
3. Hot Water comes from intake and returns to the radiator (just below radiator cap).

I disconnected heater holes from intake, push water through with my homes water holes and water freely moves out of disconnect heater hose at the radiator.

Just to be sure there isn't a restriction in the heater core, I am running some CLR in it now, just to be sure.

Engine is running right at 1st line on my temp gauge, if sometime slightly before this 1st line. Water temp after AC Type Vacuum Water valve is 150~160. Water temp on hose coming out of Heater Core hardly reaches 100, most times 80~90 (using laser temp gun). I do have a new-ish water pump (about a year old). I disconnected heater water hose from radiator while engine is running and I get maybe a trickle stream of water or none at all.

So, what should I be seeing (water wise) coming out of the heater core to the radiator return line? My only test I haven't done is see how the water is coming directly out of the intake. BTW, when I say water I actually mean 50~50 Antifreeze/Water that is full up.