2013 1500 5.7 Lukewarm heat on driver side, hot on passenger

[Beatewithaheater]

Little to no heat and pressure on driver side, full heat and pressure on passenger side.
When turned to AC, both driver and passenger have full AC and pressure.
-Replaced thermostat with a 203 temp
-Temp going into heater core 195
-Temp coming out heater core 189
-Drain and filled the coolant with both upper and lower hoses (didn't have time or tools to do a full flush)
-After 20 minutes of running truck is at 163 operating temps
-Takes 30+ minutes of sitting to reach 203
-Checked the actuator door in front and works, can't seem to find the apparent second one.

 

[jws123]

Flush the heater core a few times see if you can un block it common thing on these trucks when drivers side has low heat the core is the issue. If that does not work its time for a new heater core I have replaced 10 of them on 4th gens its not as bad of a job as some make it sound takes about 7 hrs also do the evaporator while your in the dash I made the mistake twice on not doing it and monts later it leaked.

 

[Flip-er]

Ditto what jws123 said.
I had same problem, flushed heater core and drivers side is much better,
I had everything flushed, the tech that did it said he used some cleaner to help.
Hope the flush fixes your problem, keep us posted please,