I have a new Heil heat pump with variable speed motor, and a new thermostat. During the day, with temps in the upper 90s, it seems to run great and cycle appropriately. At night, though, the blower motor ramps up really high (loud) and runs continuously. Tech came yesterday and said the coolant was low, which was probably the problem, so he charged it up. However, it's the middle of the night now and the blower is running full-out, even though the set-temp has been reached. Anyone have any ideas as to why, when the temp is lower outside, the blower runs so hard?