I need help and advise from anyone who is familiar with a Eutectic plate refrigeration system.

I have 3 refrigerate trucks, all with eutectic plates. The problem is, on first purchase, they worked fine but after a few months, each started having issues.

The problems started gradually.

I have a Mercedes Eutectic plate refrigeration system with stainless steel plates which works like fire, but recently, I noticed one side, quite close to the edge no longer freezes on all the plates along that side.

Then I have 2 IVecos with metal plates Eutectic; Now, one is a Eurocargo and the other is a small truck. The problems are identical. The eurocargo has about 6 plates in total, but 3 works, 3 dont cool at all. The 3 that works, only one cools very well and quite quickly. But when I first bought it, it was super. The smaller Iveco, same issue, out of 5 plates, oly 2 works, the other 3 has no cooling.

Now, on this aspect, I am not very knowledgeable and technical but I would appreciate any advise given simply and clearly. We have cleaned the condenser for the Eurocargo and that did help with the 3 plates that cools quite abit. Especailly, with the one that cools fast.

We have also tried adding gas, but that don't seem to be the issue. We are struggling to find a qualified engineer to truly check this out due to where we are. Its hampering the usual.

Some people say its chemical in the plates, I feel its just water which might need replenishing. Simplistic, I know. But I truly dont know much at all about this plates and their maintenance.

Please help anyone.