LR3 heater problem
 

My sisters 2005 lr3 heater is not functioning correctly. the fan works properly however the driver side vents blow cold to room temp air, whereas the passenger blows hot air just fine. I dont know anything about these cars. does it have 2 seperate heater cores? I dont see it as a thermostat issue otherwise the passenger side wouldnt get heat either. the IP control seem to work correctly. stumped

Hello,

I'm having the exact same problem in my LR3. I know it's been a while, but do you remember what how you remedied this one-sided heat problem? Thanks.

Replace the heater core ,problem is that the heater core is plugging up and hot coolant only flows on half of the heater core . did a couple in Canada for this exact fault.

How big of deal is it to replace the heater core? Any DIY instructions?

Mine still does this after the heater core being replaced just the other day. What about resetting the control level in the HVAC unit?

Hey killerpav, it is definitely a flap calibration issue, or sensors, or programming. I am in a village in the Middle East with no access to a LR dealer, but I read somewhere that there is a solution in SDD that addresses the left side going cold after a dead battery. Good luck, please let me know if you find a solution.

Lex

To the OP: I hate to ask a question like this, but you made this observation while manually controlling the fan and the temp on each side, right? Because on Auto, the LR3 could very well be controlling the overall climate by mixing hot and cold air out of either side.

Heater AC set / reset sort of procedure.
 

Below is a service procedure from a Land Rover HVAC service instruction sheet. Note also my comments below as to how the procedure actually worked for me.

The motor and flap operation can be checked using the on-board distribution motor self-test function.

The self-test can be initiated by pressing and holding the ECON and RECIRC buttons while turning the ignition switch to the ON position.

The control module will then compare the current motor position with the values stored in the module and will indicate an error by flashing the ECON LED (light emitting diode).

If there are no errors, the LED will go out and the system will function normally.

To confirm that there are no errors, turn the ignition switch to the OFF position, then back to the ON position.

Observe the operation of the programmed defrost LED.

If there are errors present, the programmed defrost LED will flash and the system will attempt to calibrate itself.

My experience was when I did above as described, with the two buttons held down, the ECON light flashed as soon as the ignition was turned on, (engine off), and stayed flashing for nearly a minute or so and then sometimes either just went out, or the fan just started up normal like and the ECONO light went out.

Then when I let go of the buttons and turned the ignition off and back on, the defrost LED stayed off as if there were no problems - never did I see the defrost LED on.

I did the test procedure two or three times and figured it failed to do anything but now I am not so certain.

Maybe the weather has just warmed up; only -20C today and cloudy, snow tonight however, but now the interior of the 3 seems to warm up more like I recall it used to - fairly quickly.

Also I did some other button pushing - that was cycle a few times, each of the air up, middle air, and foot well air switches that are mounted on the left side. I started with the heater on Auto showing the two little round LEDs illuminated on the fan control; then pushed the left upper air button and let the fan run for maybe a minute; then pushed the middle button and pushed off the upper, and let the fan run for a minute or so; then the foot well button and turned off the middle button.

I did that a few times, each time seeing if air would flow out of the appropriate vents. I also manually turned the fan up to full speed so that when air did flow, there was a real blast.

What I was doing was manually trying to cycle the air doors on the chance that one or more doors just might be sticking and would perhaps un-stick themselves.

I think I may have solved a problem even if I was not certain I had one.

I have seen a few things cause this, from the heater core clogging up, the blend motor failing, and even the blend door flap in the heater box failing, both mechanically, and from the seal melting/deteriorating.

The best way that I have found to test it is as follows.

Turn Econ on, set to a medium fan speed and face level vents, and let the engine warm up.

Set one side to hot and the other to cold(not all the way, but one notch before full hot/cold)

Check temp coming out.

Change one temp to match the other.

Check the air temp again.

Reverse temp selections that were first set, one hot one cold.

Recheck temps, and then both to the same setting as above, and check one last time.

Feeling is usually enough of an indicator, no thermometer needed.

By setting one to hot and the other to cold, you limit the path of air passing over the heater core, so if it is clogging, you will still get warm air on each side by doing this. It might not be as warm one side to the other, but it will be far better then with both sides set to warm.

If the blend motor or door itself has failed, there will not be any change of temp when going from hot-cold to match the other side.

If a blend motor/door issue is found to be the case, the motor can be removed, and the door manually moved. This should give full heat on the side that there wasn't before. If it is not, then it is either the door itself not sealing, or the heater core is blocked up and wasn't checked properly above.

Ok well I replaced the heater core and put a new battery in her. Heat moderate on passenger side (LHD) and colder on the driver side. That is with both temperature setting on hot. If I turn the driver side to cold, it gets cold. I am thinking there might be still air inside the core and I have to keep bleeding it (maybe). I never had a problem before the core got replace. I am gonna give roverguy7's idea a go and I will let everyone know.