Weird HVAC Issue

[2000BoxS]

Hello fellow 986 owners.

Ever since I purchased my 2000 986 S, its HVAC has been behaving weirdly. By weird, I mean that the blower doesn't spin and there is no air output. I can control everything on the climate control unit, except for the AC (AC icon doesn't come on the screen when I press the snowflake button). The four electric flaps/valves (part number for one of them: 996 573 917 00) move erratically and make noises. The bar indicators on the climate control unit for fan power change on its own even in "Manuell" mode.

Here's what I did so far:

- Replaced parts with tested and functioning units:

Blower motor
Final stage ("resistor")
Climate control unit
Actuation heating relay (#18 on top of the fuse box)
Ignition switch

- Checked the voltage at one of the the electric plugs for the valve motors and the voltage continues to fluctuate rapidly. All four valves work without issues when 12v is applied to them at the motor connectors in both directions.

- Tested continuity among the electric connectors of climate control unit, the blower motor, resistor, and the four flaps. All connections are fine indicating no broken wires.

- Confirmed there are no broken fuses (under the driver side).

- Checked for foam pieces that could block something in the airpath. Surprisingly, the foam pads on the trap doors are intact.

- Noticed that the AC relay is missing so I ordered one (trunk relay box #4). This probably explains the AC not turning on, not sure if it can be the cause of all the other behaviors, especially looking at the AC wiring diagram attached.


Is there anything I missed? Anyone had a similar issue?

Thank you for your help.