Arrived on 15 October for a full tuneup blue club change filters in the house upon section of the unit noticed that the union had a small gas leak was able to take the union apart clean the meeting surface reinstalled retested with soap bubbles no leak was present. Inform the customer of a previous condition of the unit was a collector box threads were damaged upon install it is not leaking at this time but wanted to reiterate the potential failure points. Cannot check gas pressure on gas valve due to stripped service port informed customer of this checked heat rise flame sensor all electrical components it is currently running at manufacture specifications at this time. Customers complaint was last winter that his 90% furnace froze up due to cold conditions previously gave customer estimate to install heat tape customer does not want to do it at this time. Thank you for your business Chris.