Came across an old 25+ Lennox HP today. No cooling. Checked and it had the usual dirty OD coil, dirty ID coil and a filthy metal mesh filter laying in the bottom of the return. After cleaning, it wasn't even attempting to sweat back, so put my gauges on it and it was 270 and 72, on a 90 deg day. Did a temp drop and had 15 deg drop across the unit, couldn't get it right across the coil. So it was cooling, but not sweating. Got to looking around the evaporator and noticed with my hand that the liquid line felt cold and wet. Traced it back and it was about 50' of 1/4" cu, and was coiled in about a 2'dia coil. Half way round is where it started sweating and feeling cool, but as I went back along the lineset, the liquid line got warmer and warmer. I remember, sort of, an old service manager of mine telling me something about coiling a liquid line, but can't rightly remember what it was and what it pertained to.Finally shrugged shoulders, said it was cooling and left.