I performed heating maintenance on a Lennox furnace. Upon arrival, the system was fully operational. All electrical components tested in their ranges with no signs of damage. I replace the return air filters as it was dirty with a customer provided filter. The furnace does not feature surge protection making it prone to electrical damage. I have created an estimate for the surge protection as the manufacturers warranty will expire in the next year. Upon departure system was operating in both heating and cooling mode with optimal temperature differentials. Thank you for being a Cool Air Solutions customer and Comfort Club member!