Need urgent help with fridge/freezer

[Northdude]

I recently converted an upright double door zanussi freezer to a fridge, first week there were no problems with it, second week the guy calls me and tells me its freezing all his food which turned out to be the relay sticking so i replaced it, 3rd week get a call off the customer telling me its too warm so i check it the following day and its fine then he rings me again and i find the evap iced up solid. The cabinet has an Eliwell EWPX174/L controller on it, i went through the parameters and found DTY(defrost type) to be set on hot gas defrost instead of electric heaters so i change it and problem solved i thought, now when i try to put the cabinet on a manual defrost i get DFU on the screen meaning defrost unavailable and the evap fan will not run when the compressor starts up (the fan was working correctly before i changed defrost settings), all door switches are working correctly but there is no live from the controller so a parameter is holding off the fan but i dont have a clue which one, i have checked fan delay time and the rest of them and they are all ok, the only other cause i can think of is the evap probe being faulty which could hold off the fan and the defrosts, here are all the parameters and settings so if anybody can shed any light on this fan and defrost problem i will be totally grateful, thanks in advance,
Dif-3,Tab-89,Hdc-1,REL-15,LSE-24,HSE-6,DTY-EL,DIT-6,DCT-RT,DOH-59,DET-15,DST-10,FST-60,FDT-2,DT-8,DPO-Y,DDL-Y,DFD-Y,ATT-RE,HAL-50,LAL-minus50,AFD-2,PAO-2,DAO-60,TAO-0,FCO-ON,CPP-DC,ONT-10,OFT-10,CTP-Dbi,CDP-2,ODO-0,PRP-EP,DEA-0,FAA-0,REL-15, Any help will be great