Got a newfangled high efficiency furnace, has 2 speeds. When on full, no problem, pumps lots of hot air out the ducts at 118 to 127 degrees.
However on low speed, it just pushes air at ambient tempature through the ducts. I put a thermometer in the duct, and the air moving is usually about 2 degrees cooler than the room temperature. Clearly in low speed the blower is running, but air is not being heated.
Am I wrong, I thought in low speed the air is still supposed to be warmed?