When my character LOAD is blue what are the negative effects if any? Green? Red I assume is very bad.

Your post fails to mention which game you are talking about. There are 8 main series Wizardry games (3 pf which are available on this website), and a whole bunch of Japanese spin-offs; which one are you referring to?

Wizardry 8. Sorry it is the only one I play.

One effect that I have observed:

Even when it's just blue, having high encumbrance increases stamina consumption.

This, in particular, impacts bards and gadgeteers, who will fall unconscious faster. It also affects those using heavy weapons, such as the tripleshot crossbow.

When encumbered enough, I have found that even conventional spellcasters have to worry about running out of stamina in long fights.

I seem to recall from my playthrough that Samurais can't activate their lightning speed ability when their encumbrance level is even blue. Not sure if it otherwise affects number of attacks for characters with higher speed.

I spent most of the game with a fair chunk of my party at blue encumbrance since it's so easy to hit and I can be a bit of a pack rat in RPGs sometimes. I didn't notice any major penalties other than the samurai one. Probably a bit of a hit to initiative and AC. Might show up in the character status window.