15 Citadel the rear HVAC has no heat, the coolant lines going to the rear HVAC box are both ice cold, so to me no coolant flow, plugged core? seems odd the front functions perfectly, i would expect that to clog up first. I have no time frame of when it quit working, I have recently replaced the Tstat and waterpump. Is it possibly just an air pocked, how on earth do you blead that spaghetti system? Is there anything else in the system that controls coolant flow to the rear? I do get gurgling in the the dash sometimes, low coolant crossed my mind due to the recent replacements of everything, however the overflow stays within range, radiator seems full, heat works in front amazingly well