Nope--both sides were set to the same temp. I even tried setting the "cold" side to the max heat setting, but that had no impact.

 

As it was 5 deg. this morning, I can really feel the difference in temperature.
At this point, I suspect my heater core is no good, but any information to the contrary would be welcomed. Note that there is really nice heat for the passenger and rear heating system. Also, in the summer, it appears that I am getting condensation from the ac, even with the ac off.
I have changed:
>All stepper motors (even double check all of them last month, by moving the flaps by hand, still no good.
>New Radiator last month.
>New thermostat about 3 months back.

Thanks,

 

If you are getting heat on the passenger side front, I doubt there is anything wrong with the front heater core as there is no left or right side to the heater core.

As you have successfully changed out the motors, I complement you as that is not a fun task however I would wonder if perhaps one or perhaps two of the motors are installed in the wrong location or are the wrong part number?

I say that as the part numbers for the recirculation motor vary according to steering wheel location so it is possible to receive the wrong motor and that it installs OK, it just rotates the wrong way.

In other words, I would suggest an air door concern and not a heater core problem.

Below are part numbers I have but they will of course changed over the years. The motors may or may not look the same, but as below, all have different part numbers.

19E616A) Recirculation JNC500010, now new part number JNC500040 for LHD
JNC500020, now new part number JNC500050 for RHD; the other 3 motors, where the steering wheel is does not seem to matter.

19E616B) Defrost Stepper JWO500010, now new part number LR041271

19E616C) Footwell Stepper JWO500020, now new part number LR041272

19E616D) Air Mix Blend JWO500030, now new part number LR041273

Below is a link to some files I have on the HVAC.

DISCO3.CO.UK Photo Gallery - Heater Air Conditioner System

 

Thanks bbyer,
I changed all of the motors, one at a time and triple checked that they were the proper ones. If I am not mistaken, the bottom motors (closest to the floor) are the ones that control the temperature. I just removed the one on the drivers side an manually moved the flap open and closed. The temperature did not change.

I have also picked up the GAP obd2 tool that diagnoses as provides live data. When I turn the temperature *****, it does show that ***** are moving.

In addition, I have been reading/researching and a truck with my mileage and issues has been a heater core in several instances.

With that said, could it be anything else other than the stepper motors?

Thanks,

 

Jpc1818; I would try flushing the heater core before removing the dash for replacement. I have diagnosed a few RR Sports with this concern but my customers don't want to spend the $$$. I get to the same point, remove the driver's motor and manually move the door flap gear but no temp change. Unless the box is not sealing correctly anymore, I would starting thinking heater core

 

I do not suppose you can find a heated parking garage or something like that so that the AC would work.

The reason I ask is that I still think it is an air flap problem. To my mind, if I am correct, the cold air should not exit on the drivers side either if there is an air flap problem. If cold air does exit, then yes, maybe it is a heater core problem, but I am thinking air lock rather than plugged.

Note the quote below from the 412-02A Front Heater Description.

The heater controls the temperature of the air supplied to the distribution ducts, as directed by the ATCM.

The heater is installed on the vehicle center-line, between the instrument panel and the engine bulkhead. The heater consists of a casing, formed from a series of plastic molding, which contains an evaporator, heater core and control doors.

Internal passages integrated into the casing guide the air through the casing and separate it into two flows, one for the LH outlets and one for the RH outlets.

When the Air Conditioning (A/C) system is operating, the evaporator cools the air entering the heater.

The heater core provides the heat source to warm the air being supplied to the distribution ducts.

The heater core is an aluminum two pass, fin and tube heat exchanger, installed across the width of the heater housing. Two aluminum tubes attached to the heater core extend through the engine bulkhead to connect with the engine cooling system. When the engine is running, coolant is constantly circulated through the heater matrix by the coolant pump. On vehicles with a Fuel Fired Booster Heater (FFBH), when the FFBH is active the coolant flow is assisted by an electric circulation pump. For additional information, refer to Auxiliary Heater (412-02B Auxiliary Heating)

Two temperature blend doors, one LH and one RH, regulate the flow of air through the heater core to control the temperature of the air leaving the heater.

On the automatic system, the two temperature blend doors operate independently to allow different temperatures to be set for the LH and RH outlets. On the manual system, the temperature blend doors are coupled together and produce a common temperature for the LH and RH outlets. On the automatic system, separate stepper motors operate the LH and the RH side temperature blend doors. On the manual system, a single stepper motor operates the two doors.

A drive arm is attached to the drive spindle of each temperature blend door stepper motor. The end of the stepper motor drive arm engages with a slot in the drive arm of the related temperature blend door.

Operation of the temperature blend door stepper motors is controlled by the ATCM. For additional information, refer to Control Components (412-04 Control Components)

All that being said, it would appear that while there is one heater core, there are two separate air streams and as such, I guess one stream passes thru one portion of the heater core and the other air stream a different portion - seems odd as I would think that the temperature spread between the two sides could be achieved by separating the air streams after the heater core.

In your case, I presume that fan pushed air does exit the drivers side, but it is not heated air, just near ambient - well maybe a bit warmed.

I gather you installed a new radiator awhile back?

If so, did the heater or AC work prior to that?

If so, then it is possible that you have an air lock in a portion of the heater core - sounds stupid, but it is not impossible that water is flowing thru only a portion of the heater core. If so, how you get an air lock out of the heater core, I really do not know but I have heard of the problem and the 3 is really bad for air locks and getting the air out. That is one reason for that bleeder tee on the small hoses under the engine cover.

Yes, the two bottom motors control the air blend doors.

I almost think you should play with the other side door manually as well; more to see if it operates as one would think it should.

Also there is a relationship between the two doors via the electronics so I would leave the stepper motor on the left side hooked up while I manually moved the right hand side door. In truth, the left side door and the electronics will not know you are manually adjusting the right door, and nothing should happen but .... What I am really hoping will happen is that for some reason, hot air will start to come out of the left side when you fool with the right air door. If so, then the question is why.

Air lock however is my best bet as that would be why a new heater core can appear to resolve the problem - it would be just that no air lock developed when refilling the system after the new heater core install.

 

Bbyers, could there be an issue with the ATCM? I figure if there was, it would throw a code but just a thought as heater core replacements and/or blend door replacements don't always seem to help. I agree that an airlock would not allow the heater core to reach full temp, but wouldn't that affect both sides? Or are you thinking trapped air on one side will significantly drop the temp?


The techs in my shop couldn't wrap their head around how there could be two temps coming from a central heater core... Makes no sense when its the downward stream from the core that gets split to either side. Both sides should be equally temp'd.


When they did the flush on my core, the water flowed through the core fine in both directions. Mind you, they were using air to push the water through so that may have introduced another bubble into the core...

 

I doubt that there is a problem with the ATCM, and if there was, it would be likely be what I call mechanical: wiring/connectors rather than the circuit board. I think all the air doors move at times however so probably the ATCM is OK plus you are manually operating the air doors at times so the problem is not air flow but temperature control.

I say not the ATCM as for some reason, the all the circuit boards on the 3 for the most part seem to be failure resistant, (I know, a pretty bold statement), but most problems with the 3 are what I call simple - well the fix is simple, but finding the problem is near impossible.

I have to agree with your techs comment that is it "impossible" to have two temps from a single heater core however I am inclined to think that there may be two separate air channels formed in the plastic heater shell prior to the air going thru the heater core.

This results in two separate streams of air to pass thru two "halfs" of the single heater core. I can envision a situation where the "top" half of the heater core has has air trapped within and it is the top half that the driver side air passes thru.

I just think the problem is something simple, but as usual, trying to figure it out is near impossible. Incidentally you did not waste your money on air motors as they go eventually anyway.

 

I picked up a new heater core and want to 100% rule out all possibilities. So, our LHD trucks, which blend motor controls the heat? I thought it was the bottom-most one on the drivers side; however, I could be wrong. As discussed earlier, I did take this motor off and moved the flap by hand. There was a very little deference in temp..

This is really annoying as I really like to heat...especially in the winter.

Thanks,

 

My understanding is that the two lower motors operate the Left and Right sides air temperature blend doors.

However given that all things UK are backwards, there is some indication that the air motor that operates the drivers side is the lower motor on the passenger side - yes - backwards. As such, fool around with the passenger side lower motor and flap and see if you get hot air on the drivers side.

The upper motor on the fan side of the assembly is called the Face and Feet Distribution door motor. The upper motor on the driver side is called the Windshield Distribution door motor. This might also be reversed because of the steering wheel thing.

As such, did you manually operate both doors? I am wondering if one door is somehow stuck or the motor operating backwards and all the heat is going to the passenger side - however I still like my airlock idea.

Below is from some LR instructions related to the air blend doors.

The heater controls the temperature of the air supplied to the distribution ducts, as directed by the ATCM. The heater is installed on the vehicle
center-line, between the instrument panel and the engine bulkhead.

The heater consists of a casing, formed from a series of plastic molding, which contains an evaporator, heater core and control doors.

Internal passages integrated into the casing guide the air through the casing and separate it into two flows, one for the LH outlets
and one for the RH outlets. (You do not suppose one of these channels is blocked with debris - doubt it but?)

When the Air Conditioning (A/C) system is operating, the evaporator cools the air entering the heater.

The heater core provides the heat source to warm the air being supplied to the distribution ducts. The heater core is an aluminum two pass, fin and tube heat exchanger, installed across the width of the heater housing. Two aluminum tubes attached to the heater core extend through the engine bulkhead to connect with the engine cooling system. When the engine is running, coolant is constantly circulated through the heater matrix by the coolant pump. On vehicles with a Fuel Fired Booster Heater (FFBH), when the FFBH is active the coolant flow is assisted by an electric circulation pump. For additional information, refer to Auxiliary Heater (412-02B Auxiliary Heating)

Two temperature blend doors, one LH and one RH, regulate the flow of air through the heater core to control the temperature of the air leaving the heater.

On the automatic system, the two temperature blend doors operate independently to allow different temperatures to be set for the LH and RH outlets.

On the manual system, the temperature blend doors are coupled together and produce a common temperature for the LH and RH outlets.

On the automatic system, separate stepper motors operate the LH and the RH side temperature blend doors.

On the manual system, a single stepper motor operates the two doors. (This is partly why I think maybe the blend door stepper motors are on sides opposite to what might make sense.)

A drive arm is attached to the drive spindle of each temperature blend door stepper motor. The end of the stepper motor drive arm engages with a slot in the drive arm of the related temperature blend door. (I wonder if the stepper motors really are moving the blend doors. That test sequence should generate movement of all the doors.)