Temperature Control Issue - Too Hot or Too Cold

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Joined
Feb 15, 2013
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5
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Apologies in advance if there is an existing post on this (I haven't been able to find any, so please guide me in the right direction if there is one).

I have a 1999 Land Cruiser 100 series. Here are the main symptoms:

- When I adjust the temperature control dial (i.e., knob that controls cold to hot settings, NOT the dial that controls fan speed), the temperature at the very lowest (i.e., cold) works okay, but is pretty cold

- When I adjust the same knob a mere one "circle" higher (i.e., warmer), the temperature gets very warm, I would say closer to hot (uncomfortably so)

- For long drives, I literally have to switch up and down between the two lowest settings, constantly, which is super frustrating and annoying for myself and all passengers, and the temp is never "just right"

Some other symptoms that may or may not be related:

- regardless of outside temp or inside temp, the entire dash (climate/radio controls) gets very hot (in fact, it feels like it's going to melt my old-school tape converter I use for music)

- the auto controls are ridiculous - if I put the temp and/or fan speed dial on "auto", the climate system goes to the extreme (i.e., full blast, either cold or hot)

I took the truck to a mechanic when getting other work done, and asked them to take a look. They apparently pulled off the dash plate, as they thought it could be dust build-up on the physical dial plate/control, but that did not work. They told me if I wanted them to fix it, they would need to spend a significant amount of time pulling apart the dash and temperature system to find the problem. They also did am electronic code read and nothing came up.

Has anyone heard about something like this? Ideally, I would like to fix this myself, but am at the point that I will pay the $000's of dollars likely needed to solve this problem. Any thoughts would be much appreciated!!

Thanks.
 
Apologies in advance if there is an existing post on this (I haven't been able to find any, so please guide me in the right direction if there is one).

I have a 1999 Land Cruiser 100 series. Here are the main symptoms:

- When I adjust the temperature control dial (i.e., knob that controls cold to hot settings, NOT the dial that controls fan speed), the temperature at the very lowest (i.e., cold) works okay, but is pretty cold

- When I adjust the same knob a mere one "circle" higher (i.e., warmer), the temperature gets very warm, I would say closer to hot (uncomfortably so)

- For long drives, I literally have to switch up and down between the two lowest settings, constantly, which is super frustrating and annoying for myself and all passengers, and the temp is never "just right"

Some other symptoms that may or may not be related:

- regardless of outside temp or inside temp, the entire dash (climate/radio controls) gets very hot (in fact, it feels like it's going to melt my old-school tape converter I use for music)

- the auto controls are ridiculous - if I put the temp and/or fan speed dial on "auto", the climate system goes to the extreme (i.e., full blast, either cold or hot)

I took the truck to a mechanic when getting other work done, and asked them to take a look. They apparently pulled off the dash plate, as they thought it could be dust build-up on the physical dial plate/control, but that did not work. They told me if I wanted them to fix it, they would need to spend a significant amount of time pulling apart the dash and temperature system to find the problem. They also did am electronic code read and nothing came up.

Has anyone heard about something like this? Ideally, I would like to fix this myself, but am at the point that I will pay the $000's of dollars likely needed to solve this problem. Any thoughts would be much appreciated!!

Thanks.



I've learned that my 2001 has some weird HVAC personality quirks....

When I shut off the windshield defroster (which was set at full hot to melt frost/ice) it will continue to send hot air up the windshield forever. The only way to prevent it is to redirect the HVAC controls to send it somewhere else (dash vents or floor vents)... but this by itself doesn't work unless I also turn on the fan motor for a few seconds. It appears that whatever mechanism is used to move the flaps internally will only function if the fan motor is also engaged.

After a couple of seconds the air will redirect itself and I can shut off the fan.

I hear you though..... it does feel like I spend a lot of time dancing between a few different combinations of heat/cold, fan speed and vent locations to keep the interior temperature well-regulated. I figured that there was some kind of defective flap diverter motor that could be replaced, but like you I also expected that the costs to isolate the problem and repair it were probably excessive and not justified for a 15-year old vehicle.


-G
 
Sounds like you might be experiencing blend door issues. Its the device that mixes the hot/cold air to get the desired temp setting. Not sure how the system completely works on your LC, but on every previous vehicle I've owned, the symptoms you describe lead to a not properly working blend door.
 
Well I'm able to use temp dial as I'd expect, but I'm with OP on not using the Auto settings, it's always full blast on those settings. As for you dash getting really hot, mine gets pretty toasty on long drives as well, but not to the point where I'd be worried...
 
My buddy ran into this with his 2000 LX. He fixed it by cleaning the temp sensor located below steering wheel near the driver's left knee. Actually in his case I think the sensor had fallen off but same principal applies. I want to say there are a few threads here on mud talking about this problem.
 
my 2003 has a mind of its own
rear air turns on automatically
its changes itself from low fan to high fan
changes itself from recirculate to fresh air
weird stuff all the time
 
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