koxka troubles

hi every one heres a strange one
got called to a koxka multi deck today which some one has already worked on :( id like at this point to add the the unit is R134a now the compressor was fitted about 9 months ago.
The comp. fitted is R404 about 6 weeks ago it packed up so the customer called fridge firm back engineer said the condencate heater has got a leak and needs replace so he's cut it out and left the system open to the elemants????
i got called to it and replaced the condencate heater vaced out the system for about 2 hours and had a nice vac weighed in 1kg of R404 then test run unit ???????
it come down to temp lovely so got paper work signed then started the job of packing up my tools. customer calles me back to say it "gone off" 13amp fuse blown checked compreespr and found it is down to earth??? why ??? i'd be glad for any advise on this one as am a bit confused as to why it's gone ALTHOUGH IT IS THE WRONG COMPRESSOR ???:mad:

thats life my friend, replace it and move on

the 404a comp has a bigger duty on it i would have said and you may find if it wasnt original one it was a bodge fix also if its been left open for a week u may have contamination in the comp also if the vapourizer was leaking it may have taken water in and coroded the comp internally moisture to wax to acid even maybe rust as the man said fit new do all you can to clean up and onto the next one u live and learn :)

also be carefull on these chillers as the little klixon bolted onto the top of the heater blows at the back and trips out the case, you wont see it till you remove it, the amount of times i have been sent to a koxka case to fit a compressor and get there and find it's the klixon!