water chiller GLAC 2015 CD1.5L

I am working on a denco happel GLAC 2015 CD1.5L water chiller which i think is a badged climavaneta chiller.The chiller works ok but after reaching set point the temp probe which is close to the plate evaporator reads 6c then shoots up to 9c in about 20 secs resulting in the compressor starting again.The trouble is it always starts comp 1,i want to vary the compressors so 2 starts next time then back to 1 as when i revisit site 3 months later comp 1 has had 815 starts and is locked out.
the probe is in a pocket,i dont know if it will work properly strapped further along the pipe and the probe is ok as it checks out with my temp thermometer. I have codes 1234 and 9990 which allow access into the user menu but i cannot find anywhere to delay start,broaden the proportional bands or use compressor last in first out.
There is another level which is the manufactures menu i could check but its 10 digit,does anyone know this password ?