I started noticing defrost issues with my Trane XL13c Heat Pump, back in December. This unit is only 9 months old. Some times when the temperature is around freezing (30-33 degrees) with rainy or moist conditions outside, my unit will ice over. If you look at the coils they are solid ice and the outdoor fan located on top of the unit is turning and vibrating but no air is blowing out the top of the unit. One would think that the Demand Defrost system would not allow this condition to happen. I understand the coils should show light to medium frost, but I thought that the unit would go into defrost by the time you start seeing heavy frosting.
Example: O.D. temp 31 degrees, Moist conditions, Coils iced up, O.D. Fan running and vibrating really bad and no airflow, Compressor access door vibrating and compressor noise louder than normal, Air from supply vent 84.8 degrees, (92.7 degrees after manually defrosting with a/c and unit returns to normal operation)
Last week my unit was icing really bad. I called the service tech and told him the issues I was having. He came to my house and checked the unit. He told me that he could not find anything wrong with the unit but said that he would order a new Demand Defrost board and the two temperature sensors. After he left, the unit started operating like it should. The unit was defrosting 3 min cycles every hour to two hours. I called the company and told them that the unit was now working but they told me that they were still going to replace the Demand Defrost board and sensors.
Two days later, the tech replaced the Demand Defrost board and sensors. My icing issues returned the next day. I called my service tech and told him that it was icing and no air was blowing out of the top fan even though the fan was running. The tech came back to my house today and rechecked my unit. He said that my issues concerned him but he could not find anything wrong. He told me that he had contacted a Trane tech about my problem, but did not tell me what the tech said. He also said that there was nothing wrong with my refrigerant pressures or the Demand Defrost system. I asked him if I should just let the unit run, although it might damage the unit, and he said that I should not worry about it, because I have a 10-year warranty. I had been switching the unit to a/c for 15 minutes, to manually defrost the system.
1) Has anyone experienced this kind of problem?
2) Should I be concerned about this issue?
3) Is this a sign of an electrical or refrigerant problem or nothing at all?
If this is a problem, I plan on taking pictures of this when it happens again and talk to the owner of the company and see what he is going to do about it. If he fails to fix this then I will go to Trane and ask them for help and to change my warranty issues to another company.
Any advice I can get would be appreciated.