First off I am doing this troubleshoot for my Dad. He has come to the conclusion its a lost cause. I feel/hope otherwise. The house is in Northern Georgia, Ringgold to be exact Near Chattanooga with a Carrier, 2.5 Ton (50YAVD48LLD311) I believe, system is Closed loop Horizontal I'll have to get back to you on the type of heat pump. The unit was probably installed back in 97 or 98 I speculate--possibly earlier. Anyhow the unit has performed flawlessly for many years however last week it went out. My sister lives at this house and claimed A/C stopped and she smelled smoke. We got around to investigating the unit and even replaced the 2 pumps on the unit with new ones we had extra. After we replaced the pumps we started the unit.The unit started, the blower spun. However no cold air, and my dad claimed when he put his hand in the tank there was no water circulation (pumps were running though). The tank near the pumps had its water/antifreeze mix, but it also had some crud floating in it-- Scale build up perhaps? If I can I'll try and provide more information, however that's all I know right now. When we got the unit we never got a manual or anything and Carrier doesn't have the YAV series on their website anymore. Anyhow, you guys are thinking just call a technician to take a look, Since its not my house its not my call and I first have to convince my Dad that it might be something that can be fixed and worth calling someone about. Thanks again and hope you guys can help troubleshoot.