Heater blowing cold

I have found that whenever it is below zero, the first 3 miles of driving our Priuii refuse to put out any heat. I turn on the defrosts [both front and back] during those first 3 miles of driving. By the time that I reach about 6 miles it will definitely put out lots of heat.

You mentioned below freezing. I have not had any problems in warm weather like that. Just when it is in the negative temps.

We drive two Priuii, both of them behave in this manner.

 

I don't think there is a heater valve, maybe someone can answer that.
Perhaps the thermostat is defective and not opening as it should.
But, in FREEZING weather, you will NOT have instant heat. The engine must warm up
to heat the coolant to provide heat. Some people block off most of the radiator with cardboard
to help speed up the heating process.

 

Hmm, that is interesting. Off and restart and the heat is immediate. I must try that myself.

Thank you.

I had pretty much assumed that a -15F car was the norm for the first few miles.

 

This is not what happens, you can not have instant heat by turning the car off and back on.

Make sure ECO is off to get better heat.

Do not use front defrost that will only bring in cold outside air, that is only used after you have the cabin heated up if needed.

From cold start it will take about 10 minutes for the engine to get to 104F.

After that it will cycle on and off to keep that temp, unless you turn the fan up.

It can get to134F with fan all the way up.
The temp is set to HI

The swooshing water sound is from the heater core, have you used any head gasket sealer?

Keep an eye on your coolant level
Since you saw overheat warning.

I am in high desert with below freezing temps so I am fully aware of the system.

 

In my 2012 there is an electric auxiliary heater fused at 50 amps that should help until the engine warms up. In eco mode that electric heat is disabled. My understanding is the inverter can also disable the heater if the 12v dc load is excessive or the inverter temperature is high.

It is conceivable that a weak or old 12v battery could be demanding a very high, maybe 70-80 amp, initial charge from the inverter. Which would be enough to disable the 50 amp electric heater.

The fastest way to warm up the engine is to drive it. In 30f weather today, my 2012 was producing heat in less than 4 minutes while traveling ~ one mile. The engine was about 110f. Within 7 minutes it was producing very hot "turn it down" heat and the engine was 145f. No rushing water sounds ever.

If you are hearing water sounds you have low coolant and air in the system. This would be consistent with the high engine temperatures you experienced. Verify the water pump and coolant levels. This is serious and could take out your engine.

 

My experience with the electric supplemental heat is that you pretty much can't tell by feel whether it is on or not.

It gives no more than about 700 watts (that is 50 amps at 14 volts), which is a fraction of the 5300 watts or so worth of heat that you get out of the coolant once the engine is warm.

Putting my hand over a vent blowing subfreezing chilly-morning air, I really can't feel the difference between whether that cold blowing air did or didn't pass through the 700 watt heat element.

Even though I can't feel the difference, I can definitely see it if the windshield is frosted and I use the front defrost. It will defrost noticeably faster with the electric heat on.

The ECO mode locks out the electric heater. I am normally in ECO mode, so I have to remember to turn that off if I've got a frosty windshield to clear.

 

Today it is not too cold somewhere between 15F and 18F. So I tried your tip.

I restarted the car three times. it had no effect. None.

 

I am willing to try any tips or tricks to better operate the Prius. I would like to know some way to get the heat going a bit faster, just in case for the days when it does get cold. We normally see temps around -20F in my township.

 

Well, as I stated on post #3: "
Some people block off most of the radiator with cardboard
to help speed up the heating process."
Kinda sounds like a sticking thermostat, or maybe you have air in the system.
And have the water pump checked. The empeller may be swelling and not moving
the coolant while it's cold. Then after the engine is off, the coolant heats up quicker, then
the engine runs, the empeller starts to rotate and you get a rush of water.

You may have to take in to someone who knows how to work on a Prius and have them
check it out. Sooner rather than later. Because you could be overheating the engine and
causing damage...