Let V be a vector space over a field F . If G ≤ GL(V, F ), the central dimension of G is the F -dimension of the vector space V /C V (G). In [DEK] and [KS], soluble linear groups in which the set L icd (G) of all proper infinite central dimensional subgroups of G satisfies the minimal condition and the maximal condition, respectively, have been described. On the other hand, in [MOS], periodic locally radical linear groups in which L icd (G) satisfies one of the weak chain conditions (the weak minimal condition or the weak maximal condition) have been characterized. In this paper, we begin the study of the non-periodic case by describing locally nilpotent linear groups in which L icd (G) satisfies one of the two weak chain conditions.