Upon arriving i ran diagnostics and found the furnace satisfies the thermostat. The customer complained the furnace was intermittently working. I began troubleshooting and noticed a lot of rust inside unit. I noticed the door switch was bypassed and had to be powered off by breaker. I then removed drain lines and blew out lines and condensate trap. Upon reassembling and power on unit unit ran with any fault codes. Upon leaving the furnace was operational.
