I have a customer that has a Coleman 18SEER 2 Stage 3Ton heat pump. The issue that I am having with the unit is that it wouldn't defrost the bottom 1/4 of the coil. The unit is sitting up on a snow stand that is 18" off the ground. I have weighed the charge out and re-weighed the correct charge back into the system. I have switched the defrost board on it. I have checked the defrost sensor to see if it was out of range (ohms out fine). What I notice when I was there last time was that the top part of the coil would heat up to 110F and the bottom part had a hard time getting up to 80F after 10mins in defrost. Has anyone had defrost issues with the Coleman or York 18SEER units?? Also I have check the reversing valve to see if it was leaking by and there is only a 1F difference between in and out on the suction side in heating and defrost mode.