76 Fleetwood Air through floor vents with engine off?

[Pghcc2006]

Good evening,

Is it normal to only get air through the floor vents with the climate control set to economy with the engine off? I know it's a weird thing to ask just want to make sure there's no weird vacuum or controller issues lol 😆

[Seville Life]

The answer to that lies in the Air Conditioning section of the Cadillac workshop manual. If you look, early in the section you'll find what is usually a vertical chart called a Function Test.

Get the engine warm, hot water available for heat and park out of the sun. Follow the test from the top, it tells you what temperature to dial up, what setting to place the control lever in and what should follow, ie, cold-warm-hot air from dash or floor vents or both.

Something is obviously wrong because with the engine off you have no vacuum source and so all the air doors in the system would go to closed position? Do the test and go from there. Paul

[cadillactim]

Air flow defaults to the floor, so vacuum is not contributing to problem.

With key on, lever on OFF, a fixed low speed is normal, as battery voltage goes from dash control through lo speed resistors in programmer (no relay involved). This lo speed is for ventilation purposes.

With key off blower should stop. Check for voltage at yellow wire at dash control. Key on, voltage; key off, no voltage. If you have voltage with key off trace that circuit back to a/c fuse and find where voltage is getting to the wire allowing the blower to still run.

Tim