Drivers side heat problem - need expert opinion

So, having heat issues on drivers side. Pass side is great. On drivers side, I get pretty much cold air through the DS floor vent, luke warm air (almost as warm as Pass side, but still cooler) through the rt DS dash vent and cold air through the left DS dash vent. Haven't really played with defrost yet. The above is with the mode in floor mode. If I go to dash mode, airflow is stronger (believe that is normal based on searching here), but same warm on rt vent and cold on left vent. If I move the blend knob from full red to full blue, the temps of everytrhing on the DS gets cooler, even the cold on the left dash vent. Therefore, I ruled out the DS blend servo.

I have what I believe is the non auto system. It is all servo based, yet does not have an auto setting. Just a temp knob (blue to red) and a mode knob.

Yesterday spent the whole day trying to flush the heater core. Hours of flushing in both directions with various different chemicals. Still getting black flakes and specks, but it takes a LONGGGG time to get them to come out. Still the same problem. Convincedd that there is still more in there, but not positive that half of the core is blocked. Still unsure what the black stuff is. It is not rubber. either corrosion or paint. You can make it break down with your fingers, so not likelly plastic.

Finally gave up and decided the dash has to come out to replace the heater core. I want to be sure that I am not getting a head fake here and this is really an issue with the servos or broken arm on a door. What makes me wonder is that I get cold air through the floor vent, yet one dash vent is warm and the other cold. Because I have not seen the inside of these units, I can't determine what that means.

I should note that the PO was an absolute hack. Everything he touched was wrong, including taking apart the trans case actuators and reassembling incorrectly, installing carrier bearing upside down, etc. Therefore can't rule out the possibility that the DS servo assy was removed and reinstalled incorrectly.

Would really appreciate some guidance from someone who has been through this.

Thanks in advance for any help.

Larry

 

Thought I would post a follow up. Replaced the heater core and now have plenty of heat. Not a fun job, but not terribly difficult. Due to being unable to rectify the source issue ( black flaky crap in coolant), i added a coolant filter before the core to avoid repeating the project.

 

Sounds like someone probably hit your truck with the stop-leak.

Best practice would be flushing the cooling system and replacing with fresh antifreeze. At very least keep an eye on your new filter and replace often until there is no more build-up.

Thank you for returning to post your resolution!

 

You may be right, but don't think so. I found a post where a guy was dealing with stop leak core blockage. He found that krud kutter got it out and showed the pics of what came out. I tried that and got nothing. In fact tried three different flushing chemicals. It was definately not rubber. Looked more like flakes of black paint. Once the core was out, I saw a lot of it come out. The core pipes go up about a foot from the core to the firewall exit and it would seem that I just could not get enough water pressure to push that stuff a foot uphill. Half the core flowed freely. All the blockage was on the far side. If it wasn't a dual heat system, it would probably not been a major issue. I just couldn't take the cold air blowing on my feet. Pass side was warm as could be.