I agree with al, it could be poor water flow or it could be the chiller baffle plate gaskets are damaged. If the chiller baffle plate gaskets are damage , the liquid refrigerant can bypass the gas passes in the chiller and the expanded refrigerant from the expansion valve doesn’t evaporate, this causes frosting of the expansion tubes after the expansion valve and also a low suction gauge pressure. If this is the case it it possible that the chiller could freeze and damage the tubes
So check the water flow rate , check the suction super heat and the suction pressure this will give us more ideas as to what the problem may be