Off Topic Rear lights.

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Off Topic Rear lights.

I bought a new ice scraper that has also a rubber scraper.
Thanks for the reminder. I shall put it on my wishlist. Hopefully Santa knows which one to buy. Of course he does. His reindeers know all about frozen tail lights.
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Yes, of course it needs more energy, but more energy doesn't mean more power. The same power for a longer time is also more energy.
Of course.

If you bought a new freezer and switched it on, it would need lots of running to get down to the correct temp. No doubt about it. The motor would run until the thermostat switched it off, then it would cycle as required.

This is the same basic idea of air conditioning.
The pump cycles on and off to keep the cooling unit cold.

Both the freezer and the air con are affected by ambient temp. The warmer the environment, the more work the pump has to do to get the freezer cold. Same as the air con in the car.

Car air cons chill the incoming ambient air and the moisture condenses off. The cold dry air is then warmed - or not - to the temp set by the controls inside the car.

However, although they cycle on and off, the load varies. The more the temp has to be cooled down, the more work - both in time and load - the pumps have to do. This is why if the car internals are boiling hot and you demand the coldest air from the air con, the power available at the driving wheels is much less ........... until the internal temp is correct (or nearly).

Regards,
Mick.
 
Mick, so basically you are saying that if the temperature is 35 °C and you set the air conditioning setpoint at 25 °C, that the air conditioning will not try to reach that temperature as quickly as possible? According to your theory the air conditioning will reserve maximum cooling power for the lowest possible temperature setpoint, i.e. 16 °C. In my opinion that isn't what happens in reality. Also for bringing down the temperature from 35 °C to 25 °C the air conditioning uses maximum cooling power in order to reach the setpoint as quickly as possible.
 
Yes.
It will try and get there as quickly as possible.
It's not as simple as On or Off.

The issue is that the LOAD is greater when the difference is greater.

Going from 5mph to 50mph on a flat road is different to going from 5mph to 50mph up a hill for instance. It's not just that the time taken is greater, but the load is greater as well.

Volume per minute ............. full throttle uses less fuel on the flat than full throttle on a steep hill. (notwithstanding wind resistance and outright speed)

Set wishes,
Mick.
 
For lenses front or rear for surface scratches I use AutoGlym Resin polish, polishes them out quite easily.

Whoa... that's dangerous, you just got the thread back on topic! :p

Good to see that nothing's changed around here (I've been busy/away for a while :eek:) - threads still going wildly off-topic with little discussion from the original poster.

Anyway; I suggest 2000-grit sandpaper, wet with soapy water, to sand the scratches out. I also use 4000-grit foam-backed discs (try a paint supply shop) to finish up after the 2000-grit. Then I hit it with the dual-action polisher and a silicone-free polishing compound such as Mezerna 2500 or Chemical Guys V36 (the latter being a bit more 'boutique' but my polish of choice).

The nice thing about silicone-free compounds is that the shine you see is the shine you get; off-the-shelf auto accessory store products tend to have silicones, which gives a nice shine that wears off after a week or two when the silicones dry out.

-Alex
 
Sounds great advice Alex. The only small comment I would add (and this may be down to differences in terminology between the UK and NZ) is that sandpaper doesn't usually take kindly to water. I would use 2000 grade wet-or-dry paper. I've never used finer than 1000 myself yet, but I haven't tried polishing out scratches to plastic lenses either.
 
Sounds great advice Alex. The only small comment I would add (and this may be down to differences in terminology between the UK and NZ) is that sandpaper doesn't usually take kindly to water. I would use 2000 grade wet-or-dry paper. I've never used finer than 1000 myself yet, but I haven't tried polishing out scratches to plastic lenses either.

Ah yes - you're right :) I did mean wet-or-dry, I'd be surprised if 2000-grit sandpaper is available in dry-only type but thank you for clarifying. We do call all types 'sandpaper' here, as the 'Wetordry' trade-name (3M?) never really stuck.

I also recommend the foam-backed discs (waterproof as well) made by Mirka or 3M (trade-only products) as being very handy for this sort of thing, as they're available in 2000, 3000, 4000, and even 5000 grit. Sanding to this level means the next-step polishing compound can be very fine and therefore give a perfect result.

A 4000-grit abrasive lacks the 'guts' to remove any scratches apart from 2000-grit scratches, which is why you need abrasives of several different grits. I suggest 1000, 2000, and 4000. The rule is to double the grit number for each sanding stage. If the scratches are bad enough, you'd need to start with the 1000-grit or even lower (the 400 grit..) but you need to finish to at least a 2000-grit level before polishing.

The soapy water (I use clothes-washing detergent) is essential when sanding softer materials, to avoid a buildup of sanding residue which might cause scratching as well as 'clogging' the abrasive material (making it less effective). The same applies when sanding a painted surface.

-Alex
 
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And I'll just add that you need to use plenty of water when sanding plastic, use only a gentle pressure and be very careful not to let it overheat.

It's frighteningly easy to burn plastic when sanding, especially if you're using power tools.

With practice, you might be surprised at how good a result you can achieve.
 
And I'll just add that you need to use plenty of water when sanding plastic, use only a gentle pressure and be very careful not to let it overheat.

It's frighteningly easy to burn plastic when sanding, especially if you're using power tools.

With practice, you might be surprised at how good a result you can achieve.
Would you recommend a very slow trickle from a hose pipe whilst sanding?
 
The problem with de-frosting without the engine running is, no matter which method you use, the inside glass steams up, especially when a body gets inside.
I've been thinking about this.

I'm not sure that you're correct, though I would expect that SOME cars would do it. Maybe it's because for the past 15 years, I've only had vehicles with air con, so the inside of the cars are always dry as a bone. Maybe there isn't enough moisture inside the car to steam up the windows?

Our air con is on permanently with the engine running, and is never switched off.

No doubt if I were wet, or breathed directly onto the glass, it would mist up, but I can't remember ever having the windows steaming up when I've defrosted them.

I'll check again when we next have a frost, but a week or so ago it was minus5 degC when I defrosted the Clio ready for Mrs Mick F to go to work, and she didn't mist up at all .......... because I'd have seen and she would have had to have waited before driving away.

As I say, I'll check again, and check properly, next time.
Frosty morning this morning.

Zero deg C.
Both cars were white all over, and so was everywhere.
Chucked warm water on the screen of the 500TA to remove the frost, and got in and started up and drove away down the drive.
(didn't do the Clio)

No misting up at all on the front window, even with two of us in.
The rear window missed up a little bit, I must admit, but because I hit the demist button, the rear window demisted and so did the door mirrors of course (though not so quickly)

At no time - even before the engine warmed up - did the front window mist up at all.

Best wishes for the season!
Mick.
 
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Chucked warm water on the screen of the 500TA to remove the frost, and got in and started up and drove away down the drive.

No misting up at all on the front window, even with two of us in.

Using warm water stops the misting because you're heating the glass. Chemical deicers make the misting worse because they cool the glass.

The downside is that you are always taking a chance that it may crack. There's no way of predicting if and when this might happen until it's too late.

You might have done it a thousand times before, but that doesn't make the next time any safer. A little too much thermal stress in just the wrong place and it's game over for the 'screen. There's no way of knowing how much is too much until it's too late.
 
Yes, warming it would make it far less prone to misting. Tepid water is probably the best compromise for effectiveness and minimising the thermal shock. Don't think I'd risk it on my screen though as it has two resin repaired chips.
 
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