Today I arrived and checked in. They relayed to me that the heat was not working and the unit was blowing cold air. I accessed the roof and the rooftop unit was attempting to finish it’s ignition cycle however this was prevented by a flame roll-out safety. The cause for this safety to shut down is a breached heat exchanger. The clients relayed to me that the A/C did function into this winter. This rooftop unit is 8yrs old and due to Lennox being closed for the holiday I was unable to confirm the warranty status for the heat exchanger. They do have one functioning rooftop unit and will be closed on Thursday. An estimate will be created and emailed once Lennox is available to confirm warranty status and part availability. Thank you, Jon Tech notes: Lennox KGB060S4DH1Y//5617C12153