Performed diagnostic on 5 year old Lennox system. Homeowner tried replacing thermostat and unit won’t start since. He tried putting old thermostat back and unit still not responsive. Checked for power at thermostat, not receiving voltage. Found a broken use on furnace circuit board. Replaced fuse, system kicked on. Cycled for cooling, system came on and is now cooling normally. Homeowner has really bad asthma that gets triggered with allergies. Recommended to replace filter more frequently than there current 6 month schedule. Also provided information on integrating a whole home air purification System to their unit. Also recommended routine maintenance done to the equipment to keep it in good condition. With homeowner approval went ahead and installed a Phenomenal Air system into unit return. Wired to a separate transformer. Also signed homeowners up on a monthly ESA maintenance program, and performed cooling maintenance on today’s visit. Checked condenser electrical and component