'Invalid' Blend Door Position from GAP Tool
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3rd Gear
Joined: Oct 2022
Posts: 3
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'Invalid' Blend Door Position from GAP Tool
This past winter I experienced what appears to be a familiar symptom for LR3s, the sudden loss of driver's side heat. Due to the lack of gradual loss I have not suspected the heater core and have focused on the control unit or temperature blend door motor. I have done a quick scan of the forum for my specific diagnostic question and haven't found it.
When attempting to diagnose with the GAP tool using live values I observed proper operation of the temperature dial (both driver and passenger sides displayed the same setpoints through range of motion), but when viewing the blend door position I received errors. Specifically, when the temperature is set to max heat on the driver side the blend door position indication moves from 'Intermediate' to 'INVALID'; the same happens when setting it to max cold or <68F. I tested the passenger side in the same manner and the appropriate positions were displayed, 'Max Cold' - 'Intermediate' - 'Max Heat' through the temperature range. I reached out to GAP for assistance and they had not seen these codes before in the live values. There are no faults relating to the ventilation per the GAP tool and the 'reset' procedure where the Recirc and Econ buttons are pushed did not return an error.
Any assistance in troubleshooting this is appreciated. If this method doesn't work I'll just pull some of the dash panels to access the temperature blend motor for physical testing. Thanks!
When attempting to diagnose with the GAP tool using live values I observed proper operation of the temperature dial (both driver and passenger sides displayed the same setpoints through range of motion), but when viewing the blend door position I received errors. Specifically, when the temperature is set to max heat on the driver side the blend door position indication moves from 'Intermediate' to 'INVALID'; the same happens when setting it to max cold or <68F. I tested the passenger side in the same manner and the appropriate positions were displayed, 'Max Cold' - 'Intermediate' - 'Max Heat' through the temperature range. I reached out to GAP for assistance and they had not seen these codes before in the live values. There are no faults relating to the ventilation per the GAP tool and the 'reset' procedure where the Recirc and Econ buttons are pushed did not return an error.
Any assistance in troubleshooting this is appreciated. If this method doesn't work I'll just pull some of the dash panels to access the temperature blend motor for physical testing. Thanks!
Rock Crawling
Joined: Jul 2019
Posts: 315
Likes: 83
From: Helsinki
I’ve actually also seen the invalid stepper position, I started a thread about 1 1/2 years ago on the D3 forum. I did get two motors, too, but have been busy enough to not look at it in more detail.
https://www.disco3.co.uk/forum/anoth...ad-203089.html
https://www.disco3.co.uk/forum/anoth...ad-203089.html
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3rd Gear
Joined: Oct 2022
Posts: 3
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Hi MrChubba,
I was never able to resolve the issue, but confirmed my blend door motors were fine. I suspected that the issue was with the HVAC control switch panel but never got around to replacing it.
The heat issue was remedied after a long heater core flush and treatment (I definitely had a plugging issue), but the blend doors would occasionally not position to where they needed to be and heat would drop out again. I would have to move the dial from hot/cold/hot/cold to 'unstick' the door. There was no obstruction, so I truly think the switch was sending a bad signal.
I've since replaced the LR3 with a Defender, moving on to another set of new LR issues to chase down.
I was never able to resolve the issue, but confirmed my blend door motors were fine. I suspected that the issue was with the HVAC control switch panel but never got around to replacing it.
The heat issue was remedied after a long heater core flush and treatment (I definitely had a plugging issue), but the blend doors would occasionally not position to where they needed to be and heat would drop out again. I would have to move the dial from hot/cold/hot/cold to 'unstick' the door. There was no obstruction, so I truly think the switch was sending a bad signal.
I've since replaced the LR3 with a Defender, moving on to another set of new LR issues to chase down.
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