Allways hot air, 92 Sub K2500

On my 92 Suburban I only get hot air even though I turn on the A/C or vent and sets the temperature to cold.
If have found the motor controling the hot/cold door (behind the glove
compartment). The door works fine and the air gets cold, when I move it to the "cold" position, but the motor turns it to "hot" all the time.
If I disconnect the wires from the motor, and manually sets it to the "cold" position, and then reconnect the wires, the motor immediatly turns to the "hot" position.
I have tried replacing the control module and the motor (with used parts). No changes. I have tried pulling a bit in all the connectors while connected, to see if I could find a bad connection. No luck.
Do you have any suggestions ? What can I expect to measure on the wires to the motor ?
Thanks Claus
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