COOL Temp Light came back on

[captainm27]

First time it has happened to me. It was so cold this week, that I was actually able to make the COOL light turn back on after it turned off the first time while the engine was still running. I had put my heater on full blast and I believe it sucked all the warmth out of the engine. First time for everything.

[IllusionX]

I don't think that's normal. Your thermostat probably doesn't close properly.

Even when the light just turned off (about 50C), putting on max heat should not make the COOL light turn back on, even with -20C temps (-4f)

[JustPassinThru]

I've never had it happen; but with another car (Geo Metro) the heater was actually able to pump heat out of the engine to where the gauge would drop back down to the COLD peg.

That was only when it was just warming up. Once the block was thoroughly warmed up, it would hold heat.

Does this happen only when it's just been cold-started? It may be nothing to worry about. You can do a crude test of the thermostat by making this happen and opening the hood - feeling the radiator and cap. If it's warm when the "Cold" light goes on, it's a bad thermostat. If it's not, then you're just sucking heat out of the coolant faster than the block is warming up.

[CTScott]

If you catch it right you can make it come back on. I found that out when I was experimenting with overriding the 4th gear prohibition when cold.

[Berkut]

Vitz very quickly cools in the winter. And if you turn on the heater to the maximum, heat that the motor is not enough. Thermostats at Toyota ever. The reason is not in it. It is necessary to insulate the engine

[captainm27]

I should have mentioned that the car was idle when this happened. I left it warm up for a few minutes, then turned the heater all the way up and the fan to max and let it idle a bit more. On Tuesday it was really cold here in Northern NJ.

[Bluevitz-rs]

It's happened to me before too. I just don't go past ••• on the fan setting. If I go to high before the engine gets up to at least 160F (I have a temp gauge in my car) the engine will start to cool off again. This also eats fuel at a much higher rate. An easy way to make the engine warm up faster is to use the recirculated air mode until you start to steam the windows up.

[IllusionX]

That's interesting. cool light supposedly turn off at around 125F ?

I usually turn the fan to max settings once the COOL light turns off, and i've never seen it turn back on. But i'm almost never idling though... so..

[Bluevitz-rs]

yeah, if you're driving non stop you're producing a lot of heat. But if you're just in the city the engine isn't and with really cold temps it pulls too much heat from the engine. Remember the heater core does the exact same job as the radiator, except the heat is pulled into the cabin.

[Berkut]

Guys, if you have a very cold winter dress warmly, vitz warm car, but he needs a little help, and then it will go up to-50C. I go to sleep but tomorrow will tell all the secrets :)))