pre-heating vs pre-defrosting

[user 4647]

Can anyone comment on what the difference is between pre-heating and pre-defrosting and what you use on cold winter?

 

[jdsx]

For what it's worth, I find there's not much difference, although in my experience the 'pre-defrost' tends to set the car alarm off more often than the 'pre-heat', so I usually use the latter. I have a 2014 car, they may have sorted the issue on later versions.

 

[elm70]

Can anyone comment on what the difference is between pre-heating and pre-defrosting and what you use on cold winter?

Pre-defrosting is the better option .. pre-heating warm up the car, but in my case it can leave the front window with "water condensation"

 

[user 4647]

And I forgot to ask, how long do you guys "pre-heat" in cold winter (-15 to -20 celcius) for the car to be actually warm when you get in? The setting on mine range from 10 min to 50min (I think). for a regular gas car I usually "remote start" for about 10 min under these condition.

 

[jdsx]

I usually reckon on 10 minutes if the outside temp is between 0 and 10 degC and maybe 20 minutes for -5 to 0 degC. We very rarely get temps below -5 degC, but for your -15 to -20, I would think 30 minutes would be advisable! But of course you guys are probably used to it, so maybe 20 minutes would be ok!

 

[user 4647]

I usually reckon on 10 minutes if the outside temp is between 0 and 10 degC and maybe 20 minutes for -5 to 0 degC. We very rarely get temps below -5 degC, but for your -15 to -20, I would think 30 minutes would be advisable! But of course you guys are probably used to it, so maybe 20 minutes would be ok!

Thanks for the info, yes we get used to these temperature but it's still nice to have a car a bit warmer than the ambiant temperature.

 

[Craigy]

So just to be clear, in pre-defrost mode it puts the heater on and also the glass heaters? So you get a nice warm car as well as clearing the front and rear screens?

 

[user 4647]

So just to be clear, in pre-defrost mode it puts the heater on and also the glass heaters? So you get a nice warm car as well as clearing the front and rear screens?

I can't talk for the other but here the temperature didn't quite drop enough for me to test if pre-defrost also warm the car.

 

[jdsx]

My car is a 2014 without the front windscreen heater, only vents for the hot air to come out. I'm pretty sure the rear screen doesn't come on during pre-heat though. I don't know if someone with a newer car could tell you....
I seem to remember the first winter I had it, I put it on 'defrost' as I wanted a clear windscreen, but that that sometimes directs so much air out of the screen vents that it set the car alarm off. (Maybe with the heated screen they've improved this on later versions.) For most winters since, I've put it on ordinary 'pre-heat', and that seems to be fine to heat the car up and clear the windscreen....

 

[msmatt]

On my Canadian 2018 model, pre-defrost turns on the rear window defrost, heating of both side mirrors, and of course the standard warm air through the dash defrost vents.

 

[twosout]

I haven't needed to use the heating but will do as the winter approaches.

I have the option for timed A/C, Heating, or Demist.
Is Demist the front screen, if you have it, as well as the rear window and mirrors?
How do you select Demist (what order do you need to click boxes etc...)?
It seems you can only ask for one type of heating per timed duration, although I assume they can overlap?
Is A/C just cooling or does it include heating (so what is Heating)?
How do I set the target temperature?
Do I need to leave the car heating system set to 'On' (or 'Auto')?
I never thought I could get so confused!

 

[user 4647]

On my Canadian 2018 model, pre-defrost turns on the rear window defrost, heating of both side mirrors, and of course the standard warm air through the dash defrost vents.

Update, the temperature is dropping and the car is in my tempo so I set the car to "pre-heat" and that seem to do ok for now. I'll see if I need to change settings for when the temperature is very cold and I'm at work as the car is outside and the window will be frosted at work.

 

[seaneb]

I haven't needed to use the heating but will do as the winter approaches.

I have the option for timed A/C, Heating, or Demist.
Is Demist the front screen, if you have it, as well as the rear window and mirrors?
How do you select Demist (what order do you need to click boxes etc...)?
It seems you can only ask for one type of heating per timed duration, although I assume they can overlap?
Is A/C just cooling or does it include heating (so what is Heating)?
How do I set the target temperature?
Do I need to leave the car heating system set to 'On' (or 'Auto')?
I never thought I could get so confused!

Didn't your car come with an owner's handbook?

 

[twosout]

Yes, and quite comprehensive, too.
But even the dealership was not sure.

 

[user 4647]

I haven't needed to use the heating but will do as the winter approaches.

I have the option for timed A/C, Heating, or Demist.
Is Demist the front screen, if you have it, as well as the rear window and mirrors?
How do you select Demist (what order do you need to click boxes etc...)?
It seems you can only ask for one type of heating per timed duration, although I assume they can overlap?
Is A/C just cooling or does it include heating (so what is Heating)?
How do I set the target temperature?
Do I need to leave the car heating system set to 'On' (or 'Auto')?
I never thought I could get so confused!

I'm no expert as we own the car only for 1 month but my understanding is that you set the timer and then you choose what option does the timer do. You can't set the timer for "defrost" in the morning and then "heat" in the afternoon as all the timer are set for the option that is choosen. To my knowledge, A/C is just for cooling. So far we have the car at 22.5c with the vent at speed level 2. I'm not sure if it make a difference or not. We have the timer set with 20 min pre-heat and the car is nice and cozy when we come in it in the morning. I'm pretty sure the vent speed is irrelevent as it seem to vent alot more during the pre-heat stage than the level 2 that I have it set up at.

Hope this help clear some confusion for you.

 

[twosout]

Thanks for the reply.
The term 'A/C' is ambiguous because it could refer to Heating/Cooling (as I think it does elsewhere) but I, too, assume it may just mean cooling.
I thought I had set it for 10min of screen demist (electric heated screen) and 20min of heating but I'm now thinking that I fooled myself and all I'm getting is (cabin) heating. It will let you ask for overlapping times.
I wonder if the heating needs to be left 'on' for it to work? And does it use the current setting for the target temperature rather than the one at the time you set it up?
If I choose 'A/C' and set the temp to 20°C, I wonder if it would heat or chill to achieve that temp, depending on ambient?
If I choose 'Demist', do I need to leave the heaters 'on'?
I can find out by experimenting but don't think I should need to do that, and the garage does not seem to have a clue...

 

[jdsx]

As far as I recall, you can't have 'heat' in the morning and 'cool' in the afternoon - it's either on 'cool' or 'heat' (or 'defrost'). You can change it of course, but you have to change it each time you set it.
You don't need to leave the heating on in the car for it to work. It works regardless of that - you get 10 minutes (or 20/30 minutes) of heat, regardless of anything else. So if the car is already at 30 degC and you (mistakenly) set to heat it for 10 minutes, it will heat it for 10 minutes....
HTH

 

[twosout]

Many thanks indeed.
I think that makes sense:
You can only control one of the effects (Cool/Heat/Demist).
The effect is not controlled by temperature.

 

[elm70]

And I forgot to ask, how long do you guys "pre-heat" in cold winter (-15 to -20 celcius) for the car to be actually warm when you get in? The setting on mine range from 10 min to 50min (I think). for a regular gas car I usually "remote start" for about 10 min under these condition.

My PHEV in defrost it can warm up around 6C every 10min

If temperature is -15C, it is needed around 30min for have he front glass window defrosted

For -15C and -20C ... I would suggest to use the maximum possible timer which is 30min ... remember to be on charger, else it will consume 2kwh from the main battery, which can reduce a lot the EV range.

 

[twosout]

I'm not sure what the power consumption is in each mode but, in heating, I'm pretty sure it's more than that provided by the standard home charger. So I think there will be an element of contribution from the battery.