And more code cleaning... I don't need yet the part to display to LCD so that's why I haven't paid much attention to it. Works the same way but with much less resources.

Code:
TempSign VAR Byte
TempDec VAR Word

'*******************************************************
'Convert temperature to LCD
'*******************************************************
ConvertTemp:

IF TempH.7 = 1 THEN
        TempSign = "-"
        TempL = TempL ^ %11110000 'bitwise invert on the 4 MSB
        TempL = TempL + 16 'adding 1 temperature unit
        TempH = TempH ^ %11111111 'bitwise invert 
        IF TempL = 0 THEN
                TempH  = TempH + 1
        ENDIF 
ELSE
        TempSign = "+"
ENDIF

TempDec = TempL * 625

LCDOUT $FE,1, TempSign, #TempH, ".", #TempL, "°C"

RETURN