I bought a home that is 6 years old. The house isn't cooling or heating as it should. Also the rooms do not heat evenly. Some rooms are noticeable colder than others. I went under the house and noticed that the return line to the heat pump was OFF! I reconnected it and cleaned the outside coil, it had quite a bit of dust and dirt built up. Neither one of these things seemed to help much. Any ideas on what might be the culprit for this poor heating/cooling house.