CODE B11FC

[birchit]

Hi guys,

my RAM 2500 2015 Power Wagon has a issue with the HVAC and letting no warm air to the passengers.

Can you help? CODE B11FC - how can I fix this air flap sensor, and where is its position? I have the shop/repair manual, but I can't find the position or anything else about this sensor.

- AC works
- Cold works
- Vents works, because it react when I change from the floor to the window or directly on the passenger
- Fan works
- Circulating air works
- Thermostate works
- Cooling system works
- Hoses are okay and warm directly at the heat exchanger
- Flushed the colling system
- Did I forgot something?

I have no further idea what I should check. When I shut of the fan I feel that the warm air which cannot come through will be stopped somehow. Is that a tempature signal thing of the sensor? Who had this same problem already or can help?

Thanks guys!!!!

Quote Quote

 

[Mister Luck]

I haven’t experienced your particular problem
Key words for a search for similar threads would be
Vent Door Actuator
But there are some tutorials in video format for several model years in google search.

 

[olyelr]

Sounds like your heater core might be clogged.

 

[birchit]

I haven’t experienced your particular problem
Key words for a search for similar threads would be
Vent Door Actuator
But there are some tutorials in video format for several model years in google search.

I watched all these turtorials. But the symptomatic shows in my opinion that it is not a vent problem, because the vents seem to be reacting when I change the are on the touchscreen. The second thing is where I can find this sensor, because of the code CODE B11FC. Is it integrated in the servomotor of the vents?

Thanks, Mister Luck

 

[olyelr]

I watched all these turtorials. But the symptomatic shows in my opinion that it is not a vent problem, because the vents seem to be reacting when I change the are on the touchscreen. The second thing is where I can find this sensor, because of the code CODE B11FC. Is it integrated in the servomotor of the vents?

Thanks, Mister Luck

Nope, more than likely not an actuator problem. Heater core is probably partially clogged.

 

[Daw14]

^^^^^^^^^^ this !!!! Heater core partially or fully clogged . Very common issue. You might try backflushing the system until it runs clear.

 

[birchit]

Sounds like your heater core might be clogged.

Nope, more than likely not an actuator problem. Heater core is probably partially clogged.

The heater core I flushed already. But it could be a blocked surface so the couldn't be an exchange of cold to warm air.
The Code says that the Blend Air Sensor Short to Battery. Now the question is where the Blend Air Sensor is located on the HVAC?
Activators: In the shop manual I found only two activators for the blends but there must be a few more if I understood the HVAC and its function correctly.

Does anybody know more...

thanks guy.

 

[birchit]

^^^^^^^^^^ this !!!! Heater core partially or fully clogged . Very common issue. You might try backflushing the system until it runs clear.

I flushed it already. But thanks for the information!

 

[RamDiver]

I flushed it already. But thanks for the information!

This may be viewed as semantics but, there is a considerable difference between flushing & backflushing.

Do you understand the difference?

Sometimes a backflushing activity requires a repeated effort or chemical support.

The reason members keep saying it's a heater core blockage is because they've seen this, many times before. And from those who have already backflushed.

If you use a laser guided temperature gauge, try measuring the temperature difference between the driver and passenger side HVAC vents.

Also, the DTC code you are referencing is not always indicative of blend door related fault.


Update:
I reread your first post and you mentioned "flushed cooling system ".

Is this what you're considering as 'backflushing the heater core'?

Please describe the method used including duration, connection points, flow direction and resulting material in outflow.

.

 

[Mister Luck]

I flushed it already. But thanks for the information!

Have you checked to see if it’s coils are clean ?

 

[olyelr]

I flushed it already. But thanks for the information!

Did you flush the actual heater core, or just the “cooling system”?

 

[birchit]

I flushed the whole coolling system, when the big circulation was active - the thermostate was open. And the heating was on maximum. Is that correct or did I forgot something important. It seems so, because you asked in this way OLYELR.

 

[birchit]

This may be viewed as semantics but, there is a considerable difference between flushing & backflushing.

Do you understand the difference?

Sometimes a backflushing activity requires a repeated effort or chemical support.



The reason members keep saying it's a heater core blockage is because they've seen this, many times before. And from those who have already backflushed.



If you use a laser guided temperature gauge, try measuring the temperature difference between the driver and passenger side HVAC vents.

Also, the DTC code you are referencing is not always indicative of blend door related fault.


Update:
I reread your first post and you mentioned "flushed cooling system ".

Is this what you're considering as 'backflushing the heater core'?

Please describe the method used including duration, connection points, flow direction and resulting material in outflow.

.

Please explain the difference of flushing & backflusing, thanks!
The temperature difference from the driver to passender side is zero. It is equal. I doesn't matter which heater setup I use, everyhting works instead of the hot air.
Flushing: I warmed the engine up so the big circulation loop will work during the open thermostate and the heating was fully open. I put the system under pressure and flushed it after it. At the end I flushed only with water by the garden hose. That's it. The outflow was clean and no dirt in there. But what I forgot to say is that I used the PowerWagon as service vehicle at the Rally Breslau 2022 - biggest Offroad Rally in Europe. So could that might cause the problem of a blocked heater core surface with brutal dust?

Thanks for your support!

 

[GTyankee]

back flushing HVAC heater core Dodge Ram, this truck is several years old than yours, Generation 3, but you get the general idea

How to Back Flush Your Heater Core by Yourself

Shop for New Auto Parts at 1AAuto.com http://1aau.to/c/87/d/heater-coreIn the video, 1A Auto shows how to flush your heater core. List of tools used:• Rubb...

www.youtube.com

This Ram is a 4th Generation, should be the same as yours, EXCEPT your Ram uses OAT coolant

Dodge Ram Heater Core Flush

My 2009 Dodge Ram has been blowing warmish air for a few weeks now. This video I'll be flushing the heater core in attempt to restore maximum heat. I also wi...

www.youtube.com

 

[RamDiver]

Please explain the difference of flushing & backflusing, thanks!
The temperature difference from the driver to passender side is zero. It is equal. I doesn't matter which heater setup I use, everyhting works instead of the hot air.
Flushing: I warmed the engine up so the big circulation loop will work during the open thermostate and the heating was fully open. I put the system under pressure and flushed it after it. At the end I flushed only with water by the garden hose. That's it. The outflow was clean and no dirt in there. But what I forgot to say is that I used the PowerWagon as service vehicle at the Rally Breslau 2022 - biggest Offroad Rally in Europe. So could that might cause the problem of a blocked heater core surface with brutal dust?

Thanks for your support!

The difference is simply the direction of flow.

You will be required to identify which hose at the firewall is on the inlet side versus the outlet side of the heater core.

If you have a laser-guided temperature probe, measure both hoses after warming the engine and record the temperatures of both for later in the process.

You might record a set of deltas with the HVAC fan set to low or off and then high.

Now you should have a delta of x degrees. The more significant the blockage, the smaller the temperature delta because the heat is not being exchanged from the air passing over the core.

Also, if you measure no significant difference with the HVAC fan set to max, this could be indicative of a blocked heater core. The delta should always increase with the HVAC fan set to maximum because the heat is being exchanged through the heater core.

The hot hose will be on the inlet side and the cooler on the outlet side.

When we backflush, we connect our water source (garden hose) to the outlet side to provide a backflush towards the inlet side. This helps to free up more of the crud collected inside the heater core.

After the backflushing process, the delta from the inlet to outlet should increase, if it was significantly blocked before you started.

This directional aspect is covered in most of the YouTube videos but if you don't see a reference in your video of choice, find another one that does. The direction is key.

Update:
My apologies but my original post had errors and I've updated the wording.

.

 

[Mister Luck]

But what I forgot to say is that I used the PowerWagon as service vehicle at the Rally Breslau 2022 - biggest Offroad Rally in Europe. So could that might cause the problem of a blocked heater core surface with brutal dust?

Let me reiterate ..
my previous post

Have you checked to see if it’s coils are clean ?

Air recirculating and circulating throughout your heater core coils theory of operation is behind the water circulation internally through the heater core itself…

… if air flow is restricted then the heat radiated from the heater core is not transferred efficiently.

check this post on cleaning and replacing cores and evaporators

 

[birchit]

The difference is simply the direction of flow.

You will be required to identify which hose at the firewall is on the inlet side versus the outlet side of the heater core.

If you have a laser-guided temperature probe, measure both hoses after warming the engine and record the temperatures of both for later in the process.

You might record a set of deltas with the HVAC fan set to low or off and then high.

Now you should have a delta of x degrees. The more significant the blockage, the larger the temperature delta.

Also, if you measure a significant difference with the HVAC fan off or set to low, this could be indicative of a blocked heater core. The delta should always increase with the HVAC fan set to maximum because the heat is being exchanged through the heater core.

The hot hose will be on the inlet side and the cooler on the outlet side.

When we backflush, we connect our water source (garden hose) to the outlet side to provide a backflush towards the inlet side. This helps to free up more of the crud collected inside the heater core.

After the backflushing process, the delta should decrease, if it was significantly blocked before you started.

This directional aspect is covered in most of the YouTube videos but if you don't see a reference in your video of choice, find another one that does. The direction is key.

.

Thanks for that. I checked the temperature of the inlet side and the outlet side and it is almost the same by measuring it with a laser guided temperature probe. So it should be blocked in any way.

Thanks for the explanaition!!!!

 

[birchit]

Let me reiterate ..
my previous post

Air recirculating and circulating throughout your heater core coils theory of operation is behind the water circulation internally through the heater core itself…

… if air flow is restricted then the heat radiated from the heater core is not transferred efficiently.

check this post on cleaning and replacing cores and evaporators

Thanks....I have checked now everything again. Sensors, flaps, the tubes and everything working correctly. What I do not understand is, if the evaporator core is blocked and the heater core as well, how can the blower bring still so much air in the passenger room?

 

[GTyankee]

On your Control HVAC Panel, does the left knob have any printing on it, that reads PUSH.
IF it does, with the engine idling & the Fan turned to the Low position,
press the PUSH button in for the count of 10 & then release, then do it again, hopefully a small light will begin to flash on the knob.

 

[RamDiver]

Thanks for that. I checked the temperature of the inlet side and the outlet side and it is almost the same by measuring it with a laser guided temperature probe. So it should be blocked in any way.

Thanks for the explanaition!!!!

If your HVAC fan was set to max and there is very little difference in the temperature from the inlet to outlet side, one of two things is happening.

The heater core is very blocked and not exchanging any heat with the air passing through the core or as Mister Luck suggested, the bulk of the air flow has been diverted away from the heater core by the door flaps not being in the correct position.

If no air flow is passing through the heater core, there will be no heat exchange.

PS: I had several errors in my previous post and have corrected the wording. My apologies for any confusion that may have caused.

What I do not understand is, if the evaporator core is blocked and the heater core as well, how can the blower bring still so much air in the passenger room?

A blockage in the heater core or evaporator is on the internal side where the coolant flows. The buildup of gunk prevents an efficient exchange with the air passing through them.

Think of the heater core and evaporator as being the same as the radiator but smaller versions, confined inside of a group of passages with a blower fan on one end and various outlet vents that are controlled by the positioning of door flaps.

I'll try to remember to post a pic of the HVAC duct system from my PC tomorrow.

If the core is gummed up on the inside where the coolant flows, that will have no reduction on the volume of air forced through the ducts and out of the vents.

Does that make more sense?


I don't recall if you have tested the outflow temperatures from the vents on both the driver and passenger sides.

Often, another indicator of a clogged heater core is a large difference in temperature from the same vent on different sides.

.