HVAC 1987 126 300sdl

[dkveuro]

Dear friends.
Is it true the HVAC sys' in this car should hold a vacuum when the car is shut off ? That is, at the a/c ...My problem is no vacuum control to any distribution vents.....A/c works with correct pressures and blows cool air but obviously not COLD because the Recirc' door is not in Recirc'. AUTO fan works, and OFF shut sys' off . There is 23 inches of vacuum at the BROWN hose prior to the fire wall. Aux' fan comes on at 290 psi hi side. I 'think' the control button head is faulty but on reflection why would system work apart from being in DEFAULT....Checked all the iATN achives but no specifics...would like to get some feedback on this please...
regards Don at DKV Euro in Purcell Oklahoma.