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Heating/ventilation Problem


drrod
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My SO has an 01 LS430. Recently she has noticed a issue with the heating system. When the car is moving, the heater puts out normal hot air as it should and keeps it at the temperature selected. The problem arises when the car stops (as at a stoplight). The air turns cold. As soon as the car is moving again, it blows warm air. It does not seem to make any difference how the control panel is set (eg. outside air, recirculation, mode, etc). The really interesting aspect of this is.......if the car is stopped and the transmission is put in "Park", it continues to put out warm air. If the transmission is in gear, the air is cold when the car is stopped.

I need to get her to check the coolant level but the whole transmission thing makes me think it is something else.

Anyone have any thoughts?

Thanks

Rod

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  • 9 months later...
My SO has an 01 LS430. Recently she has noticed a issue with the heating system. When the car is moving, the heater puts out normal hot air as it should and keeps it at the temperature selected. The problem arises when the car stops (as at a stoplight). The air turns cold. As soon as the car is moving again, it blows warm air. It does not seem to make any difference how the control panel is set (eg. outside air, recirculation, mode, etc). The really interesting aspect of this is.......if the car is stopped and the transmission is put in "Park", it continues to put out warm air. If the transmission is in gear, the air is cold when the car is stopped.

I need to get her to check the coolant level but the whole transmission thing makes me think it is something else.

Anyone have any thoughts?

Thanks

Rod

I have the same problem and think it's related to changing the water pump (coolant drained). The coolant level is correct but I'm wondering if the cooling system has air in it and needs to be "burped". Has anyone else run into this problem and have a fix?

Your heater working in Park is likely due to the increase in RPM is creating additional coolant flow. I have the same behavior.

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the 1uzfe has no bleeder valve for the engine as some honda's etc do. the air is purged thru the overflow tank cap and the sensor on it that goes bad and leaks coolant. notice how radiator cap is on overflow tank. most ppl with 1st gens jb weld or use some other king of sealant. i used oil/crank FIPG. more than likely your coolant is low. My car had coolant in the overflow tank but blew cold air. I mixed 1 cup coolant w/ 1cup water and if brought the level on the tank to the stock level and heat blows hot ever since. but over time my coolant would leak from the sensor. if anyone has stick sweet smelling gunk on your overflow sensor the it need replacing/removal. some replace most see it as unnessary and remove it. some Sc400 owners even install a tank w/o the sensor/leak area. just some things to consider...

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Hi,

I am not sure about the 01 ls, but the 98-00 have a 10 mm Hex plug on the top of the throttle body assembly for coolant system air release. I found htis out from a Master Tech @ Lexus (Thanks Len!). I have used this when I did TB/WP recently. I removed the plug and filled it from here. SLOW but effective.

I checked alldata, but could not see the throttle body assy. for 01 430's.

Hope this helps

Fblonk

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