Costumer stated that front thermostat was not working . It was set for heat at 73 and was 71 in space . Found that the unit was short cycling on limit . My return air was 94 degrees and supply air 154 degrees . Found a gap where the unit sits on the curb and supply drop . I sealed the gap using metal tape . Turn power back on and checked operations . My return air dropped from 94 to 75 . My supply air dropped from 154 to 140 . My supply air was still to high . I adjusted the pulley to speed up the rotations. After doing that my supply air dropped down to 131 with a return air of 76, 55 degree TD . Heat is operating properly . Costumer also said she turned on the ac and the space never cooled down. I turned on the ac and checked operations . System has an economizer and it completely opened when calling for ac . Outside air temp is 49 degrees . System is working