Heater core flush

[Ironcitykid84]

I have a 2013 Dodge Ram 1500. No heat from the driver's side vents. I plan on flushing my heater core and the rest of the system. Several videos I've seen on YouTube say that one of your inlet hoses should be hot and the other cool. Both are mine are hot so I'm confused. Is the top hose the inlet or the bottom one?

 

[tron67j]

The top hose on a radiator is the return, so follow that back.

 

[Jeepwalker]

There are a number of possibilities to consider.

1 - Blend door actuators. First off.... does your truck have auto-heat/cool? If so, you want to be 100% sure your blend door little electric motors are actuating properly. They often fail. Get a free scan at Autozone...if their scan can do blend doors. Or identify other issues. That should be first and foremost, b/c no heater core flushing will do anything if the blend doors aren't actuation properly. Even if it doesn't have dual auto heat/cool, ensure the actuators are doing their job.

Bear in mind, even if the motors are good, there's always the remote possibility an HVAC door hinge is broken...or where the door motor hooks up. Any cold air bleeding past a blend door (damaged foam??) can let cool air past and 'spoof' heater core issues. A scan should tell you if there is a fault of a blend door 'sweeping' fully open and closed. If you've seen foam blow out of the vents or heat duct, that could point towards blend door gasket damage ...where they can't seal like they should. A scan could also point to a failed HVAC humidity sensor too. A failed sensor could cause heat/cool issues too.

2 - Coolant Temp. Is the engine operating at the proper temperature? Ensure it is. An engine running at 160*F doesn't throw much heat..but the hoses could still feel 'hot' ...er at least really warm to touch. Don't necessarily trust the gauge. Put an IR heat temp gun on your truck's upper radiator hose. And the heater hoses. If it's not in the 195+ range... figure out why not. A lot of times poor heat is a symptom of a failing head gasket (esp if you hear 'gurgling' after first-start, or when you begin to drive away from your house, in the AM. If your truck's been using coolant ...resolve that issue first.

3 - Heater Core. Back-flushing might help. I've literally had a lot big wads of 'crud' come out of a heater core when back-flushed (not my Ram..but other vehicles). My elaborate strategy was just to jamb the open end of a running garden hose up to the heater core outlet. Messy..but did the job. Then flushed both ways. And that can restore heat.

4 - Plugged heater core. Sometimes a heater core's fine passages can get plugged esp in the center areas. Even though the outer passages could flow coolant....it's really the center where a lot of the airflow is. You could try putting a bunch of CLR in there and letting it sit a long time ...see if that opens it up. Then try flushing it out. That 'could' damage the heater core...but what do you have to lose?? When center passages get plugged usually trying to get a 'chemical' to eat out calcified plugged passages in the fine center passages, is nearly impossible ..and can add up to a waste of time. Replacing with new (OEM) could restore heat ...where it could heat a small house again.

So there you have it. There can be a handful number of things to investigate and rule out. Best of luck!!

 

[Wild one]

Not sure if anybody does this anymore,but years ago it wasn't uncommon to flush / back flush the heater core,then hook the hoses up in reverse till next winter,and then repeat the process except reverse the hoses back to their original positions.
Learned that trick from the old guy who owned the local radiator shop,swap the "in" and "out" hoses on a yearly basis while doing a flush and he claimed you'd have alot less heater core issues.

 

[Jeepwalker]

That used to be a lot easier when vehicles had regular heater hoses with clamps (not special fitted/bent lines).

 

[Wild one]

That used to be a lot easier when vehicles had regular heater hoses with clamps (not special fitted/bent lines).

Still rubber hoses at the firewall

 

[GTyankee]

The hoses where they pass through the Firewall will Both be Hot, just one of them, the Return Line will be slightly cooler

You may know that the hose fittings at the firewall are difficult to get to.

I have been thinking, it did not hurt much

I was watching videos ..

Being as it is so easy to remove the Air Filter Box completely
Would it be that hard to disconnect the 3 way Valve, that is under the air filter box.
Then FLUSH the HVAC heater from there ???

Otherwise use the Hoses where they are up at the Water Pump area

video

Gen 4 2013 Dodge Ram heat on passenger side, cool or warm on driver side.

Gen 4 2013 Dodge Ram heat on passenger side, cool or warm on driver side.I flush the heater core to fix the heat, no heat problem.Follow up video:https://you...

www.youtube.com

 

[Wild one]

The hoses where they pass through the Firewall will Both be Hot, just one of them, the Return Line will be slightly cooler

You may know that the hose fittings at the firewall are difficult to get to.

I have been thinking, it did not hurt much

I was watching videos ..

Being as it is so easy to remove the Air Filter Box completely
Would it be that hard to disconnect the 3 way Valve, that is under the air filter box.
Then FLUSH the HVAC heater from there ???

Otherwise use the Hoses where they are up at the Water Pump area

video

Gen 4 2013 Dodge Ram heat on passenger side, cool or warm on driver side.

Gen 4 2013 Dodge Ram heat on passenger side, cool or warm on driver side.I flush the heater core to fix the heat, no heat problem.Follow up video:https://you...

www.youtube.com

The OP has a 13 going by his avatar,so he might not have the 3 way valve,as that's only on the early 8 speed trucks

 

[Sherman Bird]

The hoses where they pass through the Firewall will Both be Hot, just one of them, the Return Line will be slightly cooler

You may know that the hose fittings at the firewall are difficult to get to.

I have been thinking, it did not hurt much

I was watching videos ..

Being as it is so easy to remove the Air Filter Box completely
Would it be that hard to disconnect the 3 way Valve, that is under the air filter box.
Then FLUSH the HVAC heater from there ???

Otherwise use the Hoses where they are up at the Water Pump area

video

Gen 4 2013 Dodge Ram heat on passenger side, cool or warm on driver side.

Gen 4 2013 Dodge Ram heat on passenger side, cool or warm on driver side.I flush the heater core to fix the heat, no heat problem.Follow up video:https://you...

www.youtube.com

I'm in the midst of replacing the 4.7L engine in a customer's 2002 Ram 1500. I have purchased the heater hoses and will replace them while the engine bay is empty!