Performed two system furnace maintenance on Goodman heaters. Perform system safety inspection and maintenance and found a couple points of concerns that were addressed with the homeowner. Downstairs furnace- 1. Found that flame sensors were oxidized and corroded this can cause complications on ignition for the furnace and heating mode 2. Inspected indoor blower cabinet and found dust debris caked on scroll wheel in walls of furnace. This is caused due to 1 inch filters not being swapped out enough 3. Static pressure was 0.71. Recommend specification is 0.50 4. Temperature rise was in range 5. System was not equipped with surge protection for longer longevity of parts on furnace Upstairs furnace- 1. Also found that flame sensor was not in good condition this can lead to failure in heating mode 2. Found an indoor blower cabinet was heavily covered in dust and debris recommend the filters are swapped out at least everyone to three months to reduce bad indoor air quality. Recommended at