Heating tune up completed on (4) 90% furnaces all flame sensors needed to be cleaned out and had to adjust gas pressure to 3.5” w/c Cleaned all heater sections with pressurized air and wet rags then sprayed ac shine All units operational on heat Heating tune up completed on rtu trane unit electric heat operational no issues Changed out all filters and washed off mini split filters and condenser Someone installed surge protectors on all 90% furnaces not sure who installed these. Closet unit surge protector has only one light lit (LED 3) Will get with Toby