Small tip for AC settings during offroading

muhtar
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Sun Dec 14, 2014 1:17 pm

I guess we are missing the efficiency factor in here. AC figures should not kw but kwh; and kwh is a unit of energy whereas hp is a unit of power. kwh is the input in here (how much energy the engine consumes over one hour), and hp is the output (how much power it produces) Of course you can use kw as power unit in here and I assure you that when you feed an electrical engine with 1800kwh, you most probably get less then %85 of it back, rest is gone as heat, some invisible light and corrosion on the metal parts. And electrical engines are quite efficient compared to our lovely combustion engines...

Split ACs are quite efficient as there is no sacrificed space, but car AC system are a bit loose that end: the heat transfer method and space issues makes them working less efficient. That is why same energy may not end up same cooling. Similarly to the car engines: similar fuel consumption is giving double even triple hp today. (my first car was a W123 Merc with 2.0 Diesel engine giving around 60hp with 8lt/100km, now my brother is driving a Audi TDI 2.0 pulling 174hp with 6lt/100km. I always liked W123 though)

I tried to do a dyno when AC is on back some time ago yet failed as AC was automatically shut when you push the throttle wide open with the car. I never heard any official figure in here and 2hp seems quite optimistic given the lap times I have got with and without AC, I reckon we are talking about a good 5+hp here. I remember reading 20hp is spent for all the serpentine belt family (alternator + steering + ac etc...) yet can not confirm if it is true or not. There is no way to conclude this discussion until someone tries this on dyno...

I personally don't see any of the cars we are driving off-road will suffer due to AC compressor though, most of them are 3+ litres with 6cyl, pretty power enough to climb any dunes with L gears as we don't push the engine to the wto rpm limits... With all my respect to [MENTION=2551]ginger[/MENTION] (sorry [MENTION=1]admin[/MENTION], it will be hard to respect your experience on sand until someone will see you in flesh on a tricycle, at least a kids scooter :serious business:) I would say if you fail/stuck it wont be because of AC on the sand, as I can promise it will definitely be the AC if you try to beat your track record on a long straight.

Just my two cents...
[MENTION=9783]Daggerfall[/MENTION]: Apart from these calculations, blowing sand is not normal at all. What is gonna happen if it rains heavily then; a tiny Dubai Watershow inside the car? As [MENTION=955]caprihorse[/MENTION] put it right, the filter is supposed to FILTER it already, better to check it. It is usually a basic DIY job, I would just check youtube and sort it myself, change if necessary...
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Abu Jimmy
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Sun Dec 14, 2014 2:16 pm

[quote=muhtar;39980]

I would say if you fail/stuck it wont be because of AC on the sand, as I can promise it will definitely be the AC if you try to beat your track record on a long straight.

.[/quote].

And I promise it will be definitely the A/C if you fail to cover the last two or three meters struggling before the top of a huge climb . ( you will experience this with more advanced levels where every drop of your engines juice counts ).
What goes around , comes around .
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Abu Jimmy
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Sun Dec 14, 2014 2:25 pm

[quote=caprihorse;39974]Horsepower (hp) is a unit of measurement of power (the rate at which work is done). There are many different standards and types of horsepower. The most common horsepower—especially for electrical power—is 1 hp = 746 watts. The term was adopted in the late 18th century by Scottish engineer James Watt to compare the output of steam engines with the power of draft horses. It was later expanded to include the output power of other types of piston engines, as well as turbines, electric motors and other machinery.

It doesn't matter what energy is driving motor or compressor, horsepower is always horsepower, it's a unit.[/quote]


I think Muhtar answered in better scientific way . still the difference varies from one car to another depending on engines power . ( the less power the more impact you will feel ) .
What goes around , comes around .
Arun Pandyat
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Sun Dec 14, 2014 5:32 pm

[quote=muhtar;39980]
I personally don't see any of the cars we are driving off-road will suffer due to AC compressor though, most of them are 3+ litres with 6cyl, pretty power enough to climb any dunes with L gears as we don't push the engine to the wto rpm limits... With all my respect to @ginger (sorry @admin, it will be hard to respect your experience on sand until someone will see you in flesh on a tricycle, at least a kids scooter :serious business:) I would say if you fail/stuck it wont be because of AC on the sand, as I can promise it will definitely be the AC if you try to beat your track record on a long straight.

[/quote]

I am driving 2000 model Pathfinder and never use A/C while off-roading. Couple of times I tried and ended up waiting to cool down the engine temperature. As [MENTION=1531]Abu Jimmy[/MENTION] mentioned I encountered the performance difference also.

This may not be applicable for the brand new cars....
momo
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Sun Dec 14, 2014 5:56 pm

I have solution for all your AC problems, just switch it off, spray water on your face and neck then enjoy the breeze with regular air: :thumbsup:
[IMG]http://www.almost4x4.com/vb/attachment. ... 2261&stc=1[/IMG] + [IMG]http://www.almost4x4.com/vb/attachment. ... 2260&stc=1[/IMG]
Arun Pandyat
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Sun Dec 14, 2014 6:22 pm

I used to wipe with wet towel... in hot season.:TT TT:
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caprihorse
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Sun Dec 14, 2014 9:36 pm

[quote=Abu Jimmy;39982].

And I promise it will be definitely the A/C if you fail to cover the last two or three meters struggling before the top of a huge climb . ( you will experience this with more advanced levels where every drop of your engines juice counts ).[/quote]
This is just a rumour, sounds like wrong gear at wrong place or better to say to find something to be blamed...
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caprihorse
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Sun Dec 14, 2014 9:43 pm

[quote=Arun Pandyat;39987]I am driving 2000 model Pathfinder and never use A/C while off-roading. Couple of times I tried and ended up waiting to cool down the engine temperature. As @Abu Jimmy mentioned I encountered the performance difference also.

This may not be applicable for the brand new cars....[/quote]
Pathfinder has one of the best cooling systems produced ever. If you you face some problems, there must be something wrong on your installation. Did you check this blog? - http://www.almost4x4.com/vb/showthread. ... ht=cooling
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caprihorse
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Sun Dec 14, 2014 9:58 pm

[quote=Abu Jimmy;39983]I think Muhtar answered in better scientific way . still the difference varies from one car to another depending on engines power . ( the less power the more impact you will feel ) .[/quote]
Yes [MENTION=1531]Abu Jimmy[/MENTION], you are absolutely correct. The cars with little power will feel usage of A/C compressor significantly more, even on the road, as the compressor wattage is constant depending on the size of the compressor (driven by the belt). Imagine you would built in a small car (Tercel) an A/C compressor from a bus... the engine would probably die (or the belt).

So the conclusion is, that horsepower taken by A/C compressor is never a percentage, but it depends on the size of the compressor and the space volume, which needs to be cooled (some modern cars have there a thermostat which is switching off A/C compressor, when they reach the set temperature). The cars with horsepower above 200 HP will never feel the difference.
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Mon Dec 15, 2014 2:17 pm

[quote=caprihorse;39994]Pathfinder has one of the best cooling systems produced ever. If you you face some problems, there must be something wrong on your installation. Did you check this blog? - http://www.almost4x4.com/vb/showthread. ... ht=cooling[/quote]

Thanks [MENTION=955]caprihorse[/MENTION] for reminding me about the blog.

I usually check the radiator water and coolant level. The radiator water looks like normal water and very light green colour. I checked the hose and leakage also. Everything is fine. Now I need to take to the garage for checking more detailed. When am taking to the garage do I need to do

  1. Thermostat check
  2. Thermostat removed Radiator chemical wash
  3. Replace the coolant
  4. Check the belts
  5. What kind of water must be filled in the radiator?
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