Customer stated thermostat display was continuesly going black after they had set the fan to on the system shut down and did not reengage inspected the thermostat noted two wire nuts located in wall which may have blocked the connectection which I corrected inspected low voltage wiring common and fan wire were loose and incorrect wire nuts had been used causing moisture to deep into the l.v. Wiring which I also corrected low voltage fuse was blown which I replaced thermostat came on at this point cycled the ac system which activated normally inspected wiring at the outdoor unit with no issues detected system cycled for about 30 minutes with no issue all operations are normal at this time.