Help!! No heat on driver side and barley lukewarm on passenger side!!

[Dodgeguyyy]

I’ve had no heat for a little over a year now. Absolutely no heat on the driver side and barley lukewarm on the passenger side vent by the window. Please help!! 2016 ram 2500 6.7l Laramie

 

[Jeepwalker]

1) What temperature is the engine when it's fully warm? If it's over 180F try this: Turn on heater..to 'high'. With engine fully warmed, feel the hoses/lines going to your heater core (inside the engine compartment). Are the lines cold or hot? If they're cold than there's something preventing the flow of coolant to the heater core. Most likely a plugged heater core. A solid back-flush could help restore the heat (do a youtube search how to do it). Or replace the heater core is a possibility (not an easy job). If the engine is running cool...160-180... then the thermostat is probably bad.

2) If the heater core lines ARE hot, then have someone with a good scanner (parts store??) check the heater door vent actuator. Or you could just go buy a new actuator & replace the blend door actuator...they're not very much or difficult to replace. There's videos how to do it. The blend door actuator is electrical and it modulates a little 'door' inside the heater box which blends heat and cool air (heater/AC) to give you the temp you need. If the blend door is not closing properly ...all the way. Any leaked air past the door, (bad seal??) will allow cold air to seep into the warm air-stream inside the heater box. If that occurs, on cold days the heater core cannot produce enough heat to overcome that cold air seeping past the door/seals/etc.

There's also a chance (slim I hope) that the blend door hinge has broken. But most of the time it's the electric actuator. It moves a lot during operation. Could also be the recirc blend actuator/door if cold air is flooding the cabin.

Good luck

 

[Dodgeguyyy]

Thank you. I just got done flushing the heater core out. Has to replace the elbow on the back line because there was a good size hole in it (don’t know how that happened) but there was some gunk in the elbow when I took it off. I flushed it back and forth several times till I got clear water. Hooked my air compressor up to it and blew it out the rest of the way. Hooked it all back up and still no heat. So I guess I will try the actuator doors now! Is there more then one I need to check?? Is there a way i can check it myself? Thanks again!

 

[crash68]

Absolutely no heat on the driver side and barley lukewarm on the passenger side

This symptom has been reported multitudes of times on this forum for being a plugged heater core. It is usually in HD trucks although more prevalent with the 6.4 Hemi.
If back flushing doesn't work, some have had success using CLR. If not it's probably time to replace the heater core.

 

[GTyankee]

There are at least 4 doors & an actuator for each door
There are several YouTube videos about the A/C functions & trouble shooting

There is the door that either lets in Fresh Air or closes off the fresh air. It is directly behind your upper Glove Compartment.
Right above the Ram's Cabin Air Filter, have you ever changed the Cabin Air Filter ?

The next door is called the BLEND Door, it has a actuator that can be seen when the bottom Glove Compartment is removed.
The Mode Door, controls whether you get Warm or Cold Air.

Do you have ash trays directly below your radio ?
Right behind where a Integrated Brake Controller is mounted ?
There are 2 more doors, hidden by the the panel that the Brake Controller mounts to.
They are called the MODE doors, numbered 1 & 2
the Mode Doors direct the Air movement from each Vent to another Vent, or to 2 Vents.

If you go to a shop to have it worked on, go to a Radiator & Air Conditioning Shop.
A good shop will have a type of scan tool, that can work each Door individually

 

[Dodgeguyyy]

Okay. So so far I have flushed the heater core really good. Changed the elbow on one of the heater core hoses (there was a hole in it). I replaced the blend door behind the glove box. I still have no (hot) heat. It is blowing warm (maybe 80°) on just the passenger side vents. Defrost, driver side vents, and rear vents are blowing cold air. I have no clue where to go from here at home without taking it to a shop. Anymore help is much appreciated!!! Thanks!!

 

[Jeepwalker]

Are the hoses good and hot?

 

[Dodgeguyyy]

Yes. Both hoses are hot. Didn’t get a temperature on them but they are definitely hot to the touch.

 

[bigdodge]

Id say you need to change the heater core. They can get gunked up enough that your not going to flush it out. The driver's heat comes from the bottom of the core and passenger is the top. It's not just one big loop in the core. It's a bunch of parallel lines. As the bottom plugs up it still flows some through the top. When your flushing it will take the path of least resistance so it's hard to get it all out.

You can try this. It's suggest changing the core and using this yearly
OTC 6043 Blast-Vac Multipurpose Cleaning Gun https://a.co/d/dzIkGth

 

[indept]

If both hoses are hot then it's most likely not the heater core, but one of the other blend doors.

 

[bigdodge]

Not true. Coolant will still pass through one vane of the core leaving 90 prevent still blocked. Blend doors aren't typically a big problem anymore.