I have a Trane DX condensor, TWA180B400EA. I was looking at the schematic today while waiting for the metasys system to send a signal to it. While looking at the schematic, I discovered that I have no idea how the time delay works as wired, and then I got to wondering why they would even have a time delay wired in the way that it is, and what it's function is on a heat pump as wired. The way that the schematic shows, and the actual wires seem to be, the time delay is on the normally closed side of the fan relay. There is also a yellow wire used to bypass the timedelay and move on to the pressure switches and to the comp. contactor. I can understand breaking the yellow with the time delay, but I don't see why there is a bypass and I really can't figure out what this particular time delay's function is on this unit. I wonder how the bypass works in relation to the yellow wire that is actually broken by the time delay. Thanks for the help guys. I just am not used to seeing this type of wiring, and Trane schematics seem a little more complicated to me anyway.