It's a big direct fired make up air unit or as my boss likes to say MAU. I don't have a wiring diagram. The serial number is AMI60K2N85460VAMV7. The first call it would light but not hold flame so I buffed up the flame sensing rod with a dollar bill and it cycled 10 times so I ordered a new rod. Next call it would not even light pilot so I jumped out a low air switch and cycled it 10 times no problem so I ordered a new switch and it worked fine for 3 days till the new switch came in. I put in the new switch and it won't work now even with the new switch bypassed. If this seems primitive to alot of you you have to work in Anchoage Alaska to see what I mean. It's not like a new TRANE RTU or even an old Mammoth or AAON. Lotta relays and TDR's and a lot of wies the same color and not numbered. Does anyone have access to or know where to get access to a wiring diagram. On the book that was left there and on the net the book says the wiring diagram is on page 23--- they lied a MAXITROL control is on page 23 and no schematic in sight.