When I try to switch on the climate control while truck is running I hear a loud click hazard lights cone on radio display goes blank and.

You said relay 6 was removed and the issue stopped. Do you mean fuse 6? Can you get a picture of what you are looking at or removing?

I suspect this is the case because they normally don't number relays but they number fuses. If it is the I would replace the light switch as this fuse runs this switch which in turn powers the lights.

However, if this is not correct seeing what you are looking at will really help figure out what this is controlling so that we can narrow it down.

Thanks