Arrived to no heat on a 1999 Goodman furnace located in attic. Upon inspection found that the system has a low voltage short causing the amp fuse to blow. System also had air flow restrictions due to extremely clogged filter. Took a deeper look into the system and have found that the heat exchanger has failed. Due to the nature of failure could not inspect all other gas components. Did test all safeties and electrical. Found a gas leak from a shut off in basement going to a different furnace. Repaired gas leak, bled air out and tested heat. System is fully operational at time of service.