Car defrosting on driveway, lesson learned

panthro · 18 Dec 2011 at 13:16

I just use an old ground sheet, reasonably heavy and tuck it under the wipers. This way all you have to do is just take the sheet off in the morning and drive away.
Either that or buy a Ford with a quickclear windscreen. I can't stand messing about with de-icer or scrapers.

Alibaba99 · 18 Dec 2011 at 16:39

Conscript said:
I was under the impression that even though the AC system wont cool when the outside temperature is below a certain level, that it would still dry the air passing through it, so would still be useful in demisting the screen.

The bit that cools the air is the same bit which dries it. When the aircon compressor is switched off due to the outside air temperature being too low you get neither.

DAnDan · 18 Dec 2011 at 17:14

MrMoonX said:
heated windscreen ***, get in start up wait a few minutes = no scraping

This!

It's so nice to be able to press one button, and watch the ice melt away in seconds.

MatteH Oxford · 18 Dec 2011 at 17:17

[TW]Fox;20824217 said:
Do I need to post a photograph of my Mk2 Mondeo with manual aircon *and* an outside temperature sensor?

I don't have the documents for my Mk2 anymore but the Mk3 manual even goes so far as to specifically state the air conditioning does not operate below 5c I think it is.

As you've demonstrated being a Ford technician is clearly no guarantee you are correct.

I would like to see a wiring diagram showing it (the temp switch) linked to the aircon system! The sensor would be for the multifunction display on your dash showing the frost warning & outside temp on a trip computer.

The aircon switch itself controls a relay which in turn switches the compressor. There is nothing else in this circuit, either electrically or mechanically, which will shut manual aircon off @ a certain temperature in a mk2 mondeo.

The only switches under ecu control are the high/low pressure switches which will shut the aircon off if the system is low on gas or if the throttle is near or fully depressed.

MatteH Oxford · 18 Dec 2011 at 17:20

Kenai · 18 Dec 2011 at 17:30

MatteH Oxford said:
I would like to see a wiring diagram showing it (the temp switch) linked to the aircon system! The sensor would be for the multifunction display on your dash showing the frost warning & outside temp on a trip computer.

The aircon switch itself controls a relay which in turn switches the compressor. There is nothing else in this circuit, either electrically or mechanically, which will shut manual aircon off @ a certain temperature in a mk2 mondeo.

The only switches under ecu control are the high/low pressure switches which will shut the aircon off if the system is low on gas or if the throttle is near or fully depressed.

So then, how is that Ford managed to create an AC system in the late 90s that is seemingly impervious to getting damaged when operated at too low a temperature which is something other big manufacturers still have not managed to achieve? :confused:

MatteH Oxford · 18 Dec 2011 at 17:33

Kenai said:
So then, how is that Ford managed to create an AC system in the late 90s that is seemingly impervious to getting damaged when operated at too low a temperature which is something other big manufacturers still have not managed to achieve?

It's just advice not to operate it below a certain temperature.....it still works. 'At your own risk i suppose', mine has worked for over two years in all weathers (on a 13 year old banger).

When it's next frosty i will go out & turn my ac on & you will see the compressor running. It works, i'll post a bloomin video of the under bonnet if you like with it spinning & the clutch engaged!!!

P.S. my car does not even have an outside temperature sensor as it is poverty spec LX with a/c. No fancy dash display or trip computer.

[TW]Fox · 18 Dec 2011 at 17:34

Will a quote from the Mk2 Mondeo Owners Handbook do you?

Manual said:
The system only functions whilst the outside temperature is greater than approximately 4c and the engine is running

Kenai · 18 Dec 2011 at 17:41

MatteH Oxford said:
It's just advice not to operate it below a certain temperature.....it still works.

So why do other manufacturers prevent the system operating underneath a certain temperature? Just for a bit of a laugh? :confused:

"Hey guys, you know what'd be funny, if we made the AC not operable below 5C even though there's no actual reason for it!!"

#Chri5# · 18 Dec 2011 at 17:42

floatindolphin said:
Why do people leave their cars running unattended? It's just foolish.

Start it, get the scraper out. Start on the driver's side window and work round the back and finish up with the driver's side of the windscreen. That way, even if someone jumped in it while you were there, they have no visibility

That's what I do as well. Bonus for me is by the time you've done all the windows, the heated seats are toasty warm

RJC · 18 Dec 2011 at 17:55

Kenai said:
So why do other manufacturers prevent the system operating underneath a certain temperature? Just for a bit of a laugh?

"Hey guys, you know what'd be funny, if we made the AC not operable below 5C even though there's no actual reason for it!!"

The evaporator I suspect would become iced up, also newer cars use Thermostatic expansion valves and these require a certain pressure differential to work correctly and at lower temperatures the performance would reduce and the expansion valve may not be able to maintain the correct S/H in order to stop possible flooding back.

MatteH Oxford · 18 Dec 2011 at 18:05

[TW]Fox;20826788 said:
Will a quote from the Mk2 Mondeo Owners Handbook do you?

Will the actual ford wiring diagram from the online Ford etis system do you?. Give me five, I'm 99.999999999999>infinity% sure I'm right.

*edit* here you go.

No temperature sensor here

406880_10150534848062889_768412888_10632006_664089980_n.jpg

[TW]Fox · 18 Dec 2011 at 18:15

So what?

Who knows why it doesn't work/shuts off at under 4c - it might automatically disengage itself, or it might be designed in such a way that it is simply ineffective and does not function at low temps (Hence Ford's wording of 'approximately'). Perhaps it's unable to acheive the correct pressure level at sub zero temperatures, hence the pressure switch prevents it from operating.

The fact remains that car air conditioning systems almost universally do not operate below about 4c.

The actual Ford owners manual for the Mk2 Mondeo categorically states that the system only works above 4c. The manual for my car says the same thing. The manual for every car with aircon I've ever read also says the same thing.

Perhaps it's a physical limitation, perhaps its a technical limitation, who knows?

What we do know, mind, is that at 0c, your cars air conditioning isn't helping you clear your windscreen.

Why does the owners manual for your car tell you that the air conditioning does not function under about 4c if it actually does?

MatteH Oxford · 18 Dec 2011 at 18:20

[TW]Fox;20827064 said:
The ony thing we do know, mind, is that at 0c, your cars air conditioning isn't helping you clear your windscreen.

Why does the owners manual for your car tell you that the air conditioning does not function under about 4c if it actually does?

Owners manuals have been know to be incorrect, especially ford.

The aircon definitely makes a difference in clearing my screen, with it off it takes ages to demist, switch it on & it clears very quickly. The system works when the compressor is running, the switches turn it off. The aircon cannot be off when the compressor is running arrrrrghhh!. **** me fox, i know when the system is operational or not!!

Just admit you are in the wrong!

[TW]Fox · 18 Dec 2011 at 18:23

MatteH Oxford said:
Owners manuals have been know to be incorrect, especially ford.

So you are right and Ford, VW, BMW, Mercedes Benz, Vauxhall (to name but a few) are wrong?

How odd they'd miss an opportunity to publicise additional and improved functionality of the vehicles they produce and instead lie to customers and pretend that they are ineffective...

The aircon definitely makes a difference in clearing my screen, with it off it takes ages to demist, switch it on & it clears very quickly.

Because it's a Mk2 Mondeo! You cannot switch the aircon off AND divert air over exclusively over the front windscreen. If you engage the front windscreen demist position, it automatially switches on the AC light. You don't get a choice. The only way to not illuminate the AC light is to not use that setting.

If thats what you are doing then no wonder it takes longer with the light off - it isnt blowing as much air over the windscreen.

It's demisting quicker at 0c because it's blowing more air over the screen not because the air condtioning is functioning normally.

When you switch to the demist setting its increased volume of air thats making a difference, not aircon, because there isn't any conditioned air at 0c.

Just admit you are in the wrong!

I'd have to be in the wrong first

MatteH Oxford · 18 Dec 2011 at 18:29

[TW]Fox;20827121 said:
Because it's a Mk2 Mondeo! You cannot switch the aircon off AND divert air over exclusively over the front windscreen. If you engage the front windscreen demist position, it automatially switches on the AC light. You don't get a choice. The only way to not illuminate the AC light is to not use that setting.
.

I'd have to be in the wrong first

The position switches run on vacuum, there is no connection from them to the a/c system lmao

I can run my system set to windscreen without the a/c engaging.

dear god

[TW]Fox · 18 Dec 2011 at 18:32

No you can't. Once you move the switch to windscreen you can't switch the AC off. It automatically illuminates the AC light to indicate it is using (or attempting to but with no effect if its really cold outside) the air conditioning.

Surely everyone with a Mk2 Mondeo knows this, we used to get people asking about it on a weekly basis when I was into Mondeos, people seem confused by it (Its the only car I've driven that does this, to be fair).

Emjeadea · 18 Dec 2011 at 18:43

I never do this but one morning i went out to the frozen car and put the engine on went back in the house to finish of my cup of tea then came back out to a policeman coming down my drive to tell me not to do this as cars are being stolen and with it being so close to christmas it wouldnt be very nice (damn right it wouldn't)

SoliD · 18 Dec 2011 at 18:46

[TW]Fox;20827161 said:
No you can't. Once you move the switch to windscreen you can't switch the AC off. It automatically illuminates the AC light to indicate it is using (or attempting to but with no effect if its really cold outside) the air conditioning.

Surely everyone with a Mk2 Mondeo knows this, we used to get people asking about it on a weekly basis when I was into Mondeos, people seem confused by it (Its the only car I've driven that does this, to be fair).

Same for the mk3, and the manual states that below 4c that the AC won't turn on iirc.

Skeeter · 18 Dec 2011 at 19:17

The demist setting in my mk2 Mondeo adopted the 'turn everything on and fire it at the windscreen' approach. It included turning the ac on.

Didn't use it much though, as the heated windscreen was fantastic, and far more effective at clearing ice than using the heating alone. Turn on engine, turn on heated screens, de ice the side windows and the front and back had done themselves.

I love heated windscreens!

In contrast, there was ice on the inside of my Clio windscreen the other day that was a right pain to get rid of.