Luke warm driver side, hot passenger side

[Lui_5793]

Got my 2013 Ram 1500 4.7l having HVAC issues. It’s starting to get cold here in Texas and have already had some weather get to 30 degrees recently. Main issue I’m facing with HVAC is that when I put heater all the way hot, with engine at operating temp, passenger side is hot but driver side is luke warm. I checked all other functions such as defrost and lower side vents but they all blow Luke warm on driver side. I did check the blendor just behind the glove box more to the center console and change the temperature on the dial but blendor looks to move freely. I also checked if both lines going to heater core are hot and they are. Is there something else I can check before considering the heater core is out? Thanks !

 

[mtnrider]

Clogged heater core, Classic symptoms. Try and back flush it

 

[crash68]

 

[Jeepwalker]

1) I would start by swinging by a parts store like Autozone or OReilly's and have them direct their scanner to your truck's HVAC module. Read codes. Perform an actuator self-test. The HVAC module will swing them back/fourth ...and if something is amiss then it should alert you via the scan tool. It's an easy way to catch something w/o having to dig too deep. Your tk might have a crapped-out door actuator. Then it is great to know which one.

2) It would be a real good idea to back-flush the heater core (that means the *Reverse* of normal coolant flow) with your garden hose. Esp being a 2014. Ya have to remove the hoses...and that's some work. Once that's done, just jam the garden hose up to the *proper* heater core pipe. There are videos on how to do. Search Youtube. You might be amazed how much 'crud' can come out of some heater cores! A lot of times that restores heat. If not, a new heater core for sure does.

3) If it's a broken blend door...then you're in for a more wild ride and lot of work. An actuator test *should* be able to tell if a blend door isn't bottoming out. The HVAC computer basically looks for a high-current feedback so it knows the blend door actuator has reached full-stop. If a door is broken off the rod, it gets spongy and keeps twisting ...or twists too much, and the HVAC module will *usually* (not always) indicate a problem.

 

[Burla]

Blend doors are f k all bad, I know someone who traded their vehicle in instead of fixing the blend door at 3500 bucks, and she loved that highlander, loved it. The issue with modern blend doors f'n plastic gears. So do you hear any rotational things at all? If you hear like any rotational clicks or noises, it's the blend door, and unless you find a way to dyi, it will cost near what it would cost for new lifters.

 

[Jeepwalker]

It could be two bad door actuators (??). They DO fail...so first thing, and cheapest/easiest thing is to do a door actuator test with a scan tool. Read for codes.

Hopefully it's not a blend door broken. Ya have to remove the dash for that. It's not TOO big if a job if ya have DIY skills and take it easy, slow. It's a lot of work, but if ya take it steady and slow, lot of guys have done it. I've done it in other vehicles a few times. The worst part is "thinking" about it ..the dread. Once ya get tools going, it's one step after the other. At least for me. There are a bunch of how-to videos on the subject. Then you should replace your heater core at that time. Ya also have to get the AC re-done. If you take it somewhere it'll definitely cost a lot in labor.

But right now it's premature to say blend doors.

Could also be a flaky controller..

Start with the test scan.

 

[LeeD]

Like was already said, flush the heater core. You might want to pick up some radiator flush too. After flushing with water drain the core or blow it out and then mix the radiator flush with hot water. Fill the core and let it sit for a while. Then flush it out again.
I had to do this almost yearly on my daughter’s Nitro.

 

[mtnrider]

While it "could" be a blend door, that was primarily a 3rd gen issue. It is almost Always the heater core on the 4th gen trucks. Start by flushing it and make sure you get all the air out of it before you get too wrapped up in anything else....

.

 

[cdn cj]

It’s definitely not going to hurt to flush the core but I seriously doubt it will resolve your issue. The heater core doesn’t decide which way to direct heat.
I’d recommend diagnosing blend doors first.

 

[jawzs2]

It’s definitely not going to hurt to flush the core but I seriously doubt it will resolve your issue. The heater core doesn’t decide which way to direct heat.
I’d recommend diagnosing blend doors first.

Actually, yes it does, the plenum is split down the middle with a baffle, the bottom 1/2 of the core goes to the driver's side, the upper half to the pass side. The bottom starts to clog first, hence low heat to one side only.

 

[cdn cj]

I stand corrected.
Never had one of these apart but it stands to reason engineers would screw up something so simple.

Actually, yes it does, the plenum is split down the middle with a baffle, the bottom 1/2 of the core goes to the driver's side, the upper half to the pass side. The bottom starts to clog first, hence low heat to one side only

 

[GRKN]

Definitely heater core, had the same thing happen last year. Flush it both ways, fill it up with CLR (calcium lime rust remover), let it sit for half an hour and flush with water again. make sure your using distilled water and bleed the system after you put it back together.

 

[Lui_5793]

Thank you everyone for the suggestions. I already want to get maintenance done to the vehicle since it’s high mileage (186k) and I bought it used nearly 3 years ago with 138k and have no idea what was done with it previously. I will be taking the truck to an independent shop and have them flush the entire cooling system, was planning on doing that anyway.

 

[Lui_5793]

I have some mechanical skills but let's say I go ahead and flush the heater core. Since I will be introducing air into the system anyway, I'd like to flush the radiator and engine of the old coolant and add fresh coolant, along with replacing the thermostat. I've been told there is a bleeder screw on the driver side of the engine (I know the location and have seen it) and that is the way to bleed the system of air. Here are my questions about all this:
1.) How would you go about cleaning the system?
2.) Is the bleeder screw a reliable way to ensure all air is out of the system?
3.) I've heard that you can flush the cooling system out with hose water but will need to refill the system with distilled water, how would I ensure I do that properly?

If any steps can be provided, I'd much appreciate it! I do have the Haynes Manual from Oreilleys but would like more input.

 

[NETim]

YT video on bleeding cooling system:

https://youtu.be/l7-cMph3lG8?si=1SwQaSyBR-4k1c

 

[mtnrider]

It’s definitely not going to hurt to flush the core but I seriously doubt it will resolve your issue. The heater core doesn’t decide which way to direct heat.
I’d recommend diagnosing blend doors first.

Oh but it does.... Clogged heater core is by far the biggest culprit here

 

[Burla]

The best known flush is rmi25, coolant does not have detergents because of what it needs to do. This product takes any clogs and any slime and deposits it into overflow. I have seen it in action myself, then you vacuum overflow. True flushes are near impossible, if someone can convince you they can flush your system let us know the process. You would use rmi 25 for 500 miles, then do the flush.

 

[bigdog85]

had the same problem with my 10 it was the blend doors were broken i traded the truck in asap

 

[Joseph Godvin]

Cores 1/2 plugged !!!! Been there !!!

 

[MAC830203]

Like everyone said, flush it. Check doors work.