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