Customer had us out due to no heat and wanting to replace T stats. Replaced customer supplied T stats per his request. Found bad heat strips. Customer decided to have them replaced under warranty. Customer needed a new disconnect for upstairs. Customer agreed to have it replaced. After replacing T stats, heat strips, and disconnect was finally able to complete full system inspection with the system running. While running we noticed issues with zone board. When T stats were calling no 24v at system side but 24v at T stat terminals on zone board. Straight wired to get customer by and tested system. Noticed outdoor unit not coming on. Went and inspected outdoor unit and found system had no refrigerant. Informed customer of findings. Let customer know we will need to do a nitrogen leak search. Customer is aware and has elected to have us return to complete nitrogen leak search. Will return Friday to preform leak search. Once we find leak and replace the part that is leaking we will need to