haldex air dryer

hello all new to your forum hope you can help...been running fh12 420 for some years nowits a version 1.. itv has the haldex air dryer system on her with a condensor next to it..right here goes, last nov 13 had new dryer fitted volvo mech said if i want he would by pass the condensor as it was not wired up anyway..had no props until last week when air kept on building up and setting of the purge valves.volvo here said had leak on the grou vave [suspension control its bolted to chassis oninner side behind cab,changed that ..still building up to much air,what else is there,or should i reinstate the condensor,thanks for any help,,