Most service calls, I don't need to refer to schematics. I can usually look and see. Even in units that have control PCB's. Today I made a service call on a 8 yr old Lennox that did not have 24vac to the coil. I traced the 24v wire from the incomming lug to the contactor. It went thru several wizzbangs before it made it to the contactor. Although I have serviced this unit this year, I have never taken the time to look at the wiring. There is a lot of crap. I just figured it was a HP so extra wiring was normal.
The schematic looked like it was drawn by a child. Labels were on part of it and missing from other parts. I am very good at reading schematics, and have read schematics from hell. Written in Italian with new names from page to page, and with alternate pages in English. I also have experience with same color wires. machines wired all in black or white wire.
This schematic was from hell. It could not be understood. Names were on 1/2 of the pictorial(if you can call a crappy drawing with no correlation to the schematic a pictorial) and missing names on the rest of the drawing. The equipment has a P&B relay, with several contacts not defined. It has another relay undefined that is using 3 contacts of 4. It also has a high pressure switch connected to a port on the acculumator with a reset button.
The schematic does not define the reset button or how it is wired into the circuit, It has a name for the reset but does not use the identifer "RESET" anywhere.
I pressed the reset, and the system reset itself and started to work. The whole process took about 30 minutes in the sun.
Since the unit belongs to my boss, I cleaned up and went home to research the problem. Any suggestions?