Hey guys, I have done a TON of research on this and other forums and cannot seem to find anything. I have a 2010 T&C 4.0 Limited and the rear heater just stopped working out of nowhere. It only blows cold air; not sure if it is A/C or ambient as it is cold outside. I have replaced the rear heater core, rear blend door actuator, flushed out the system, checked for a clog by running hose fed water through the rear return line. I can sometimes smell coolant but have dismissed a leak because it doesn't appear that I am losing any coolant, and I am attributing it to coolant that was soaked into the firewall cloth guard from when the heater Y-fittings blew out (I replaced with T-fittings instead of the cheap Y-fitting). I am running out of ideas, I thought maybe the T-fittings have something to do with it but I am pretty sure I used the heater a few times after that fix... I was going to replace the heater blower resistor but read somewhere that it only affects the fan operation and has nothing to do with the heat. Also, I just had a new motor put it but this issue was from right before that happened. After the new motor install the front heater stopped working as well for a while and out of nowhere it started working again. This is driving me crazy, any help will be greatly appreciated.

 

Replacing the Y fitting with a T could be the problem. The Y fitting will evenly distribute the heat from the engine to both heaters but a T fitting will, depending on which way round you installed the fitting, will cause the hot water from the engine to take the easiest route through the connector. Try swapping the output pipes on the fitting to see if the hot water is biased more toward the rear heater.

 

Thanks, I'll try to find a better quality Y fitting than the OEM and Dorman ( from O'Reilly's) because I have already replaced with those, and they both ended up blowing out. I'll see if that is the issue, If you have any other suggestions I'm all ears...