MainePorsche

Guys,
All of a sudden my Heater Valve does not function as it should.

When I tested the valve with a MityVac, it functions normally.
Stepping motor functions as it should.
Very strong vacuum just past the check valve off the MC.
Only 3 in Hg vac at white line to heater valve. Measured on hard line - not rubber coupler.
On simple inspection all colored hardlines appear connected and things 'look' normal under the center console.

Is there a suspected place I need to go but don't see yet ?

Add: Also, is the white hardline a single line from the module to the heater valve or is it joined somewhere behind the console ?

Thanks in Advance.
Craig

MainePorsche

Got down into the center console - all vac lines attached (I did do some work there recently with the central locking unit). I noted I had no vacuum in the black source line. This narrowed the search for I had good vacuum at the lines' origin. Found what is pictured under the cowl at the union of the two hard lines. Didn't know there was a union there. Checked and tested all other lines and their function normal. All works once again. Thanks.