Came out for no heat call on 2018 Lennox AC/90% Furnace. Upon arrival customer let me know shortly after I called to give ETA, the system came back on. Visually inspected furnace and drain and found vinyl tubing sitting outside still partially frozen. System has condensate pump with a safety float switch. Issue was water in tubing froze causing a back up which tripped condensate pump float switch. When I arrived temps already rose above freezing so issue was no longer present once ice began thawing. Spoke to customer and mentioned that main permanent solution would be to keep tubing inside then fully encapsulate crawl space so it never reaches freezing temps. For immediate solution recommended running tubing to condensate drain in crawl space then fully insulating to help prevent freezing. Also recommended signing up for our Home Care plan for 2 systems for 3 annual visits, priority service and 10% discounts on our services. Customer agreed on repair only for today. Ran tubing to conde