Air conditioning at Yeep Grand Cherokee 97

Hello everyone, I have a problem with the defroster motor. I think that's what the motor that blows air towards the windshield and the interior of the car is called.
When I turn the knob to the power position, I only hear the relay click; the motor doesn't start. Voltage is reaching its connector, but I'm getting a reading of positive on both terminals. If I disconnect the connector and connect it directly to the battery, it starts.
I think it's missing a ground connection because when I apply chassis ground, it starts, but the panel doesn't control the speeds or power. If anyone can help me with this problem, I would greatly appreciate the assistance.