I am trying to revive an old three phase 5HP HVAC system so I took a look at the 25 years old electrical system digram and came across 3 three sections which I could not understand completely (I am not en expert) highlighted here :

enter image description here

I became curious about their purpose and I am hoping some of you might be willing to help me answer these three questions:

  1. What is the purpose of those #1,#2 wires on the J1 jack (highlighted in GREEN)? they seem to be connected only to the J1 jack and dont continue through the P1 port.
  2. Which relates to first question, what is the purpose of the low voltage transformer's N1 neutral connector (highlighted in RED)? the transformer seems to get neutral from the N2 wire which leads to the main neutral through the 7-wires "TB" socket. it also appears that the N1 wire leads directly to those two wires I mentioned in my first question.
  3. Lastly I would appreciate an explanation about the function of the indoor fan motor component highlighted in BLUE. does it relate to the rotor's spinning direction?

I haven't got much enough experience with these kinds of diagram so any help is extremely appreciated, sorry for my English.


Some things are shared between models

The N1 neutral terminal and pins 1 and 2 on J1 are probably used on a different model unit that shares that control board, but not used on this particular model. This allows the manufacturer to save on costs by making one control board instead of two almost-identical ones.

As to that wacky part...

Since the manufacturer was unhelpful and failed to label the part you circled in blue, I can only guess at its nature -- it's most likely simply a connector between two motor wires.

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  • Hi ThreePhaseEel thank you very much for your comment, I accept your explanation about the #1,#2 wires as it seems like they have no use at their current state. would you recommend disconnecting them completely? regarding the weird component part I manged to take a picture of it and you were definitely right! these is a two motor wires connector: the manufacturer did mention some info about it in (highlighted in the blue rectangle) – tultal4 Aug 26 '17 at 16:35
  • here is the picture: i.stack.imgur.com/JuA6M.jpg . since its an air fan blower I suspect it might have a way to control left-right motor spin direction. could this be the job of this part? – tultal4 Aug 26 '17 at 16:45
  • @tultal4 -- the connector is part of what controls the motor spin direction yes. to reverse it, swap the brown wire in the connector with the orange wire attached to the fan motor's capacitor. – ThreePhaseEel Aug 26 '17 at 16:59
  • OK thanks to you now I can understand the system better. you have been very kind and helpful since your the only commenter :) thanks again. – tultal4 Aug 28 '17 at 15:25

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