pjmas

2004 Lexus LS430

Sitting still the heat blows cold. But when I am on a highway or driving up a hill pushing the gas it works like normal. Anyone have a similar issue? Just trying to see if its something I can do before having to take it to the dealership.

Thanks

rkw77080

The LS430 heater uses engine coolant to provide heat to the cabin. Based on your description, I suspect your coolant level may be low. That is, when you raise the engine RPM, the water pump sends more coolant through the heater coil to provide more heat. Have a look and let us know what you find.

Fixman

I second that. When engine is coled. Check coolant level in the overflow low tank and radiator. Top up start the engine and run the hater.

Johnhav430

Seems to be a common issue that our coolant evaporates from the overflow...when I got my car in Oct. 2016, there was no coolant in the reservoir, nor was there any to be seen in the radiator, yet the level was just fine. Also, with low coolant, my heat worked fine.....if you top off Toyota red should be ok--I'd want to get it replaced anyway if it is low (this indicates it likely didn't get any attention). Even green is safe--never use Dexcool (orange). I've heard when you mix coolant types, then your system takes on the properties of the one that needs to be changed to soonest (say you have long life, but you add green--now your time/mileage takes the property of the green).

Also, do you have this sensation on all vent positions? Just so it's not a moving target, meaning, when you switch from vent to bi level to floor to floor def, etc., is that changing properly? I've not heard of actuators failing on our cars, but have on other makes...

biacs

I'll bet coolant level. You need a phillips to remove the cover that sits over radiator. Also I bought a new OEM radiator cap online. Old pressure seals are always suspect. And it seems to have been holding but I had the white crust around the overflow.

I also replaced the rubber line from the overflow. I think folks have them swell and leak as an aging issue too. Money well spent.