pushbutton control unit or someone wired the servos -- with no vac you should have full defrost only. However, if the fan does not respond to the buttons, it's the pushbutton unit.

Either replace it or take it apart and re-solder everything.

You can pull the connector off the monovalve and see if you get full heat all the time -- if not, you have a circulation problem of some sort with the heater core, of so, PBCU.

Verify that the aux pump is OK BEFORE replacing the PBCU -- if it is drawing too much current, you will promptly fry the new PBCU.


Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!