'96 VDP - Heater blows 'warm-ish', not hot

1996 VDP ~250k miles
Heater only blows ‘warm-ish’ air at HIGH, not blistering hot like it used to.

So far:
I pulled the heater auxiliary pump and it was a dead short.
Bought a heater pump for a Transit van ($50 as opposed to $581 for the Jag-brand) and installed it.
Since I had to solder on the Jag harness connector, I double-checked impeller rotation to make sure it ran the right way.
Checked voltage at the connector and it’s 14V with engine on.
BUT, the hose going to the heater matrix is not as hot as the supply hose to the valve as it comes down the sidewall.
AND, the voltage to the Valve is 14V when the heater temp control in the cabin is all the way DOWN, and only 6.8volts when the heater temp control is at 90.
The SAME temp of air blows with the heater temp control set at 90 or way down low (but not to A/C range).
Heat does NOT increase when the valve connector is disconnected (that is, when it should be fully open).

The valve is the problem.
I assume (and have read) that the valve is a normally-open voltage-driven proportional valve and it is stuck in a partially-open position.

Should I replace the valve or try a repair?
I ask, because 250k miles is a lot of cycling on that valve.

The valve is normally closed so try disconnecting it.

I thought it was normally open, i.e., no voltage applied = open.

I have tried disconnecting the leads to the valve and running the heat.
And, there was no change in out put temp of the aor.

So, (now I think more clearly about THAT result) either way, NC or NO, the valve may simply be stuck in a partially open mode.

Does my thinking make sense?
(don’t ask my wife!)

Sometimes the heater matrix gets clogged. You could try reverse flushing it. The procedure has been described here on the forum.

A flush is certainly a good idea. Thanks for the idea.
I’ll have time in the next couple of days to splash myself with cold water on a cold day.
: - )

I did the flush - it seemed clogged (water spraying back at me for a few seconds) then it ran free BOTH directions.

I tried the heat - ‘maybe’ a small change?

But not blistering-hot air like it used to be.

Now I’ll run the push-two-buttons-and-twist-my-nose diagnostics.

Good luck! I am having disagreements with my climate control, too and am out of ideas what to test.

Gee, Harry, that’s encouraging.
: - )

Let’s both keep poking at our cars until something breaks entirely.

Have you checked the thermostat?

OK, now I feel stupid.
I’ve blown right by that suggestion in 15 different threads I’ve researched on various forums.
[smacks forehead]

I’ll do it today!