demist/defrost hybrid

[Enterprise22872]

Hi all, I am new to these forums and sorry if my question has already been answered, but I think this question probably applies to all hybrids. I currently have a 2019 petrol Yaris and I'm thinking of changing it to a hybrid Yaris. How does the defrosting/demisting of the front windscreen work when presumably the engine doesn't always spin up when you start a hybrid? Obviously the heat generated by the engine helps clear the screen in a few minutes, but if the engine is not switching on or staying on for long enough when the car is initially started, does it have to rely on the cold air or is there some sort of heating element that generates warm air?

 

Thanks Pete.

  

[Anthony Poli]

Hi Pete,

When you switch on the heater, the engine will fire up to provide the heat.

Normally the engine will start with a few seconds unless you press the EV button, I can only speak for non plugin hybrids, as I haven't had the plugin type to drive.

 

[Catlover]

As Anthony says above, plus you would presumably only be using the demister on colder mornings, so there is a very good chance the engine will kick in anyway.

[Starensis]

Some higher end models have a PTC heater, which is like a kettle element. This allows quicker warm up. Also, some use exhaust heat to assist warm up.

Typically, on hybrid ( as mentioned ), engine will run until coolant is heated enough to supply cabin temp.

[Enterprise22872]

Thanks all. Yes, the last couple of days I have to clear the frost from the windscreen and it got me thinking. I presumed the engine would have to come on when started, otherwise you would be in a catch22 situation whereby you couldn't clear the screen as the engine wouldn't be on to supply the heat, and you couldn't drive away to start the engine as it would not be safe. A heated windscreen like they have in the fords would be better!

 

 

[TonyHSD]

Toyota self charging hybrids use the heat from the engine coolant to heat up the cabin and clear the windows therefore engine would start to run to warm up itself after the car been off for some time but when you have been driving it for a while or been seated in the engine might not be running all the time and you still have heating coming to the cabin. These cars has an electric water pump that circulates the coolant through the heater core even with internal combustion engine been off, this gives the car ability to be silent engine off and to provide heat and clear the screen. Air conditioning though as with all other cars will not switch on and help clear the windscreen when outside temperature is below 4C°. Conclusion: Toyota hybrids operate like standard cars in terms of heating and cooling with the difference that the internal combustion engine works less time and you still have heating and cooling. The Air conditioner compressor is also electric and works on the high voltage power from the hybrid Battery, again in hot summer days you have cooling and no engine is needed to run all the time. 👍

[Enterprise22872]

Thanks Tony for the great explanation.

[TonyHSD]

1 hour ago, Enterprise22872 said:

Thanks Tony for the great explanation.

You are welcome 👍

[Cyker]

TBH the heating in petrol is an order of magnitude better than it is in hybrids and diesels. My old Mk2 1.33 would get to operating temperature by the time I got to the dual-carriageway but with my old Mk1 diesel and this Mk4 hybrid on cold days like this I can get half-way to work before the engine gets to operating temperature!

I had the Mk4 on while de-icing the car this morning and aside from the rear windscreen at mirrors (Both of which have heating elements on mine ) there was practically no heat going into the car. Even when driving, the engine was always running but precious little heat. Partly the problem is the engine is so efficient there isn't much waste heat, and I really feel this car could do with a PTC heater in it!

Even with the AC on, because the air was so cold the demist windscreen button didn't really do much and I ended up just wiping down the inside of the windscreen and rearview mirror because I knew it would take virtually forever to heat up while sitting there idling.

I think if your main concern is heating in the winter, the smaller hybrids are not the best cars to go for.

Where the Mk4 really shines is in the summer, mpg well past 70 and the AC can run without the engine so you can have AC without the pain of seeing the fuel gauge dropping twice as fast!  

 

[flash22]

PTC's are never an option in the UK as we don't get the cold weather pack, most are fuel based and preheat the cooling system (one of the big OE's Webasto) electric heaters are for BEV's but the older Hybrids Nimh packs don't really have the current/voltage

-6 here this morning started the car, cranked the heater to 22, stuck on the front and rear defrost while getting the ice off and getting numb fingers it was just right after 10 mins

lowest ever MPG today of 46 but i don't think it got over 4ºc all day

[FROSTYBALLS]

Also see:

 

[Cyker]

28 minutes ago, flash22 said:

PTC's are never an option in the UK as we don't get the cold weather pack, most are fuel based and preheat the cooling system (one of the big OE's Webasto) electric heaters are for BEV's but the older Hybrids Nimh packs don't really have the current/voltage

-6 here this morning started the car, cranked the heater to 22, stuck on the front and rear defrost while getting the ice off and getting numb fingers it was just right after 10 mins

lowest ever MPG today of 46 but i don't think it got over 4ºc all day

That's a good point... It'd be hard for the Mk4 to drive a 4kW or even 2kW PTC heater for any useful amount of time with its 0.7kW traction Battery  

But my no-HVAC coat-on tactics are working, still 68.7mpg!!! I do rue the lack of heated seats and steering wheel the Euro-spec ones have tho'...!

 

[Stopeter44]

14 hours ago, Cyker said:

Even with the AC on, because the air was so cold the demist windscreen button didn't really do much and I ended up just wiping down the inside of the windscreen and rearview mirror because I knew it would take virtually forever to heat up while sitting there idling.

 

It's dry around here, but the night we took delivery and drove home the aircon was turned off, and it was decidedly cool, it didn't take long to mist over inside. setting the A/C to automatic fixed it quickly. It's very rare to have drizzly weather here, but when I lived oop north (France, that is) it was common, I've always found the air conditioning very effective.

[bathtub tom]

I've found it very effective to put a hair dryer on inside the car while I have a cuppa, but I do have secure parking.

[Cyker]

That's exactly the sort of thing that, if I did it, I'd come back and find my car is on fire  

 

[Mikw]

3 hours ago, Cyker said:

That's exactly the sort of thing that, if I did it, I'd come back and find my car is on fire  

At least your screen would be defrosted.... 🙂

[FROSTYBALLS]

16 minutes ago, Mikw said:

At least your screen would be defrosted.... 🙂

Yes but would it be from the hair dryer or the fire ....

[Roy124]

The handbook says that as the car uses stop/start as it switches from EV to ICE and back it will always start the ICE first thing to bring it up the Temp. 

The Car Nut explains that the Toyota software controls the coolant flow directing and restricting water flow to minimise unwanted cooling and maximise component heating all for economy. 

Compared to a diesel ICE my hybrid comes up to temp more quickly.