ac fill level check window (bubbles thing) connector..????

[natorious]

ok well i decided to figure out whats up with my AC and why its not working... first thing i checked was the fill level window thing....

and notices the plug on the side was unplugged and the connector was jumped with a jumper wire... anyone know why this may be...

what is the purpose of this plug...

i havent had a chance to look in the bentley yet as i forgot it at my fiance's place last weekend