Tantrix

can anyne help, the heater doesn't work. it's set to the highest temperature setting.

It only works when car is driving steadily faster over 25 mph. seems like the heat from the engine coming into the cabin.

is it the water pump or thermostat ?

hfahmy

Top off you coolant

Chuckinnj

Air bubble, bad thermostat, low coolant to name a few possible causes.
Is the engine getting hot after 15 minutes of idling?

shinbob

I had a coolant leak that I later fixed, but what I noticed was that the coolant levels didn't have to fall very far in the reservoir for the heater to stop working. It was still above the "low" line when I stopped getting heat. I had to top it off all the way to the "full" line to get the heater to work.

So an easy thing to try is to, as others have suggested, top off the coolant all the way to the full line. Use the proper coolant (for my 2010 is was the Toyota long life pink stuff)

Kennyr44

Most likely needs a Water pump and a thermostat to go with it. Look for the pink residue on the bottom of the pump.

greg3852

As others have said, check the coolant level before doing anything. If it is even slightly below the full line Ive had issues like this. I would then check for any leaks.

Tantrix

Thanks guys.

how does the pink coolant amount affect the heating and cooling capabilities in the cabin ? I thought the radiator specifically only regulated the engine temperature. Sorry in advance for lame question.

Htony

Because coolant does not flow in full volume. Thermostat directs hot coolant to cabin heater core. Ever done a pressure test for the cooling system? Feel upper hose and lower hose to see if there is difference in temperature. Replacing pump is bigger job plus $$. Replace cap, thermostat and make sure you fill the rad. when it is cold. Then
fill over flow tank to the mark. Hope there is no air pocket in the cooling system.

egolfer

I had the same problem on my 08 LS 460. I took it into the dealership and they told me that it was a bad radiator cap. Charge me a hundred bucks for the cap and the heating system was back to normal.

Htony

100.00 for a cap? Maybe they flushed system and refilled for the price? Cap is not that expensive.

thoiboi

Classic stealership markup, nothing to see here...

Tantrix

I'm assuming they topped it off before giving the car back to you. But wow really ? The radiator cap ?

Chuckinnj

My suggestion is to take your car to a Toyota or Lexus mechanic...... To avoid potential damage to the car and yourself.

klyn75

i just bought a 2007 model and right away i noticed the heater only worked when car was rolling. the mechanic said it called the blend door actuator

Doublebase

The blend door is not affected by the vehicle moving or not, it's moved by an electronic actuator...has nothing to do with vehicle movement or speed.

Like others have said, low coolant could certainly cause the loss of heat. A blend door actuator could certainly do it too, but it wouldn't have anything thing to do with driving. A stuck open thermostat will cause a loss of heat. On and on. But the easiest thing to do is check your coolant level.