Any what this part is (in the real world)?

[DrJeff]

I'm toubleshooting the fans coming on (or rather not) with the AC being switched on (the otterstat is switching them on). I've got most of the electrical diagram figured out but the purpose of the thing/connector (see red arrow in picture) is not clear.

18679

It looks like just a connector joining the incoming switched power (LGW) with the run to the compressor/fans, a strange feed through a capacitor, and then providing power to the fan switch. Hmm?

[Ron]

Look's like you could use a Schematic Legend. (http://dmctalk.org/showthread.php?17-DMC-12-color-wiring-diagram&p=101620&viewfull=1#post101620)

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It's a Mode Switch.

http://i47.tinypic.com/2djzzg6.jpg

[David T]

For the cooling fans to be forced on when you put the mode switch to AC or MAX the low pressure AND high pressure switches have to have continuity. If you have no Freon (or are low) the compressor clutch will not engage and the cooling fans will not come on. As you note, they will only run against the Otterstadt switch. Does the compressor clutch engage? If not then the system is acting normally, you are probably low on Freon.
David Teitelbaum