Have a 2000 Jeep Grand Cherokee, the heat works blowing out of vent but when I turn it to cold it barely blows anything out
The ductwork has blend doors that move to get the temperature to the vent where you want it. The blend door that throttles hot/cold is sticking because the door actuator is defective. You may have noticed a tapping sound under the dash from a defective actuator. Try a spray lubricant on the actuator, or remove it to see if there's a broken sprocket. Might need replacing. It's not a difficult fix.