Electrical connections for fresh air fan

[EJP]

I am looking to remove the lower part of the fan box and need to disconnect the 3 wires to the fan.
I have found the connections for red one and the blue/black one. Could someone please tell me where you disconnect the black wire (ground?) so the fan box can come out? Does it disconnect down inside the fan box?
Could not find anything on this doing a "search".
Thanks for your help.

 

[EJP]

Found it! The fan ground wire is attached to one of the studs that hold the top half of the heater box. It is a closed loop connector. Had to loosen all 4 of the upper fan box nuts to get the wire off of the stud. There is not enough play in the plastic housing to get the wire off loosening only the stud it is attached to. I guess if you were removing the entire fan box the ground wire would have been obvious, but that wasn't my initial plan. The red wire and blue/ black wire for the fan are located above the gas pedal. They each have their own plastic
housing at the connection point.

 

[Jefco]

I think finding the wire on top of the plastic housing is a sign the heater fan has never been removed before, most people would just snip the wire at the base of the ring terminal and replace it on top of the stud on reinstallation, or splice the black wire (with or without a connector).
Are you replacing your heater core, or just the fan?

 

[EJP]

Jeff, This started as a replace the heater control valve job. Nuts were pretty rusty where the valve met the heater core so I decided to take out the core to get the valve off. After the core was out, I figured, take out the fan box too and clean up the insides. That's when I ran into the search for the ground wire. Thought about as you suggested to just cut the wire and resplice late, but I like to make things difficult for myself. Have to get the core cleaned and tested for leaks although I read somewhere on this site from one of the regular contributors that the cores rarely leak. Guess I'll find out. By the looks of things taking it all apart, it doesn't look like any of this stuff was ever removed before.
Ed