Houghton H2000C Owner's Manual page 18

 When you have heard 4 clicks and the end of the duct
is firmly parallel to the top side of the bracket then you
have successfully connected.
Loop
II
Click
These two faces
are parallel
Installation of the plenum assembly
 Connect the socket and plug of the display panel wires
and the controller wires; please notice that colors of
the wires should be matching ( yellow to yellow, red
to red, etc );
 Attach the plenum assembly to the plenum mounting
bracket by engaging the two parts. You will hear four
clicks to as the parts connect together.
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