m800 AC retrofit and some questions

anupmathur · 24th June 2009, 13:28

Quote:

Originally Posted by eternalck

, i will make sure the rpm stays constant at just above idle to prevent the readings from varying a lot.

Those numbers are probably for full load operation of the compressor. That would quite possibly be at an engine rpm of about 3000.
Keeping the rpm just above idle would not be good enough.

As for a measured quantity of gas, Maruti would be able to tell how much R12 used to be filled in the old M800s. Assuming your system is now about 10 to 15% larger than that (due to R134a charge requirement being 10 to 15% less than with R12), the same weight of R134a (instead of the earlier R12) ought to do the trick.
It is always easier to identify an undercharged condition and to rectify it by gradually charging gas from the LP side (no liquid charge on the HP side please).

eternalck · 24th June 2009, 14:21

can you please clarify why those values should be at full load and not on the supposed rpm the readings should be measured? am i right when i guess, that when the rpm would increase when the car would be moving, the pressures would also increase and hence the cooling performance would decrease? but won't the increase in wind across the condenser compensate for this increase in pressure (as would have the radiator fan done if it was directly connected to the engine and not the electric ones we find now).
then i think that keeping on the lower side of the pressure values on the chart should do the trick, cause judging the 3k rpm would be a difficult task.

yes that suggestion is a good one about the quantity of r12 which was used to be filled would be approx. equal to r134a now on the bigger system.

but the thing is, it just doesn't feel right draining all that gas to the atmosphere and contributing to global warming even more than driving this car around ( maybe this gas does not harm ozone, but r134a is 1000 times more efficient than CO2 in causing global warming, as you might be aware :() i want to try removing some pressure first.

but yes if this doesn't work out then this method should do the trick.

anupmathur · 24th June 2009, 18:41

Quote:

Originally Posted by eternalck

....but the thing is, it just doesn't feel right draining all that gas to the atmosphere and contributing to global warming even more than driving this car around ( maybe this gas does not harm ozone,

Hey, the correct way to do the job is by collecting the gas into a receiver, not venting it to atmosphere!

Obviously this quack does not have a proper charging station or any suitable equipment.

eternalck · 24th June 2009, 19:11

do you seriously believe that these illiterates, who possibly don't know how to fill gas to the right pressures, know about refrigerant recovery equipment, and the harms these gases pose?!

it just makes me wanna hit them when they carelessly vent these gases into the air. thank goodness that r12 is not quite available now or we would be bathing in UV radiation!

hey you did not answer the other part of my post

anupmathur · 24th June 2009, 20:29

Ah, the numbers!
It would make no sense to quote them for anything other than at the rated capacity. Don't you think so?
I am not aware of any defined standards that are followed for quoting car AC compressor performance figures. But that's because this is not my line.
I just feel the figures would be for full load operation under some defined ambient temperature conditions and other peripheral equipment that is mated to that compressor.

eternalck · 24th June 2009, 20:41

i'm seriously considering buying those gauges. but ebay doesn't have them, do you know where i can get them?

anupmathur · 24th June 2009, 20:50

Quote:

Originally Posted by eternalck

i'm seriously considering buying those gauges. but ebay doesn't have them, do you know where i can get them?

Why do you want to spend so much? These are not gauges that you'd typically be using even once in five years!
The lesson to be learnt from this episode is that cheaper sometimes means losing ALL the money! Fortunately, it's not been that bad for you. Had you opted for Maruti in the first place, there would, most likely, have been a pretty professional job done.

eternalck · 24th June 2009, 22:05

actually the problem to go with maruti was that i would have had to spend about 50% of the car's market value!

ya you're probably right again that the gauges wouldn't be of much use after just once.

so i will just have to approach a 'mechanic' tell him to please follow what i say, and i would give him his fees without him applying his brain on it...

eternalck · 28th June 2009, 01:52

i had one mechanic lower the refrigerant, and voila its now chilling like crazy, in the evening when it was 38C outside!!

The stationary low side pressure was at 50psi when it was about 42C outside. Naturally when the car would be moving it would come down to about 40psi, nearly the right pressure.

Even in the hot sun the coil is extremely cold, the air is cooler than before but the culprit is the hot dash that is making the air hotter as it comes out, i guess a windscreen film would sort that issue out...

But the main problem now is that old oil (r12 type) is lying inside the compressor and some new oil was lost when the gas was released into the open air again

.
So i will have to search for a reputed ac shop and have them disassemble the whole thing and drain that old oil and put new gas in with the oil.
But all this can be done next year in the start of the summer. So i have plenty of time to search

.

Another problem is that still i don't know how much gas goes into the system, maybe the reputed shop'll know about it, or i'll go about with your estimate. But still i can try the same steps as i did this time if nothing works.

Thanks all...

scorpian · 28th June 2009, 10:22

U can get this fixed real cheap...go to any a.c spares shop.buy a tipco compound gauge(75rs),buy two charging lines(80each)and a hand gauge with two openings,with a hand valve(120rs).

Now u can check the pressure(running/standing) and do it urself,if you are running 134a please note that the quantity of gas required as compared to r12 is much lower,for example in deep freezers which ran on r12 if the back pressure is kept at 10psi,then the same in r134 is 6psi,a typical thing about 134a is that u need lower gas for it to give u best cooling as compared to r12.This holds very true and i haev seen and personally experienced this many times while working on coldcel freezers,when we would maintain the same pressure as r12 the cooling would be largely inadequate.

Since ur based in delhi which has a huge a.c spare part markets u shud get this spares for real duirt cheap,even cheaper then what i have posted the prices...

eternalck · 28th June 2009, 10:43

thanks for that info scorpion, i'm probably gonna get those soon now!
i am just thinking if it would be harmful for the compressor to operate with lesser oil... but then i think that they probably over filled the oil too

by the way scorpian, do you know the amount of gas a can of r134a holds?? and are there newer charging ports (r134a ones) available which could be hooked on to the lines next year when i have it opened up because these older ports have a lot of leakage whenever a hose is being connected to them.

and one more thing, these 'mechanics' say that they don't measure the high pressure side cause air would get into the system if they did (!?), another load of cr*p which they speak of

. one was even saying that the pressure is the same with both sides!

scorpian · 29th June 2009, 21:46

Hi,
u get ready cans of 134a,made by honeywell and marketed by whirlpool,the can contains 500gms of 134 and is in its purest form which is really great for automoblile use since moisture is a problem when charged from big cylinders,hence the handy can is of great use,the can retails at rs 240/-but like i said earlier since ur based in delhi u will get this spares for dirt cheap since delhi has one of the biggest refriegeration spares market....

For use of 134 u will need couplers to fit on to ur car charging suction line,this again are easily available and u can buy them for as low as 300/- they cum in a pair, high side and a low side,pls be aware charginf from high side is risky,but yes it is absolutely neccessary to check pressures on both side for the best possible cooling,

An easier way is to charge the low side and keep checking the mirror on the bottle,also touch the thicker pipe (suction) this should have good sweating on it...if you overfill u will experience not so good cooling as well as ur car running real sluggish,in mpfi vechiles if u overcharge the compressor starts clicking on and off...

While charging its a good practise to splash water on the condensor.....

Its a very easy process and u will eventually manage it,once ur satisfied with the cooling just note down te pressures so that next time u can just top up incase u run down on gas..

24th June 2009, 14:21	#77
eternalck BHPian Join Date: Nov 2008 Location: New Delhi Posts: 175 Thanked: 94 Times	can you please clarify why those values should be at full load and not on the supposed rpm the readings should be measured? am i right when i guess, that when the rpm would increase when the car would be moving, the pressures would also increase and hence the cooling performance would decrease? but won't the increase in wind across the condenser compensate for this increase in pressure (as would have the radiator fan done if it was directly connected to the engine and not the electric ones we find now). then i think that keeping on the lower side of the pressure values on the chart should do the trick, cause judging the 3k rpm would be a difficult task. yes that suggestion is a good one about the quantity of r12 which was used to be filled would be approx. equal to r134a now on the bigger system. but the thing is, it just doesn't feel right draining all that gas to the atmosphere and contributing to global warming even more than driving this car around ( maybe this gas does not harm ozone, but r134a is 1000 times more efficient than CO2 in causing global warming, as you might be aware :() i want to try removing some pressure first. but yes if this doesn't work out then this method should do the trick.
	() Thanks

24th June 2009, 19:11	#79
eternalck BHPian Join Date: Nov 2008 Location: New Delhi Posts: 175 Thanked: 94 Times	do you seriously believe that these illiterates, who possibly don't know how to fill gas to the right pressures, know about refrigerant recovery equipment, and the harms these gases pose?! it just makes me wanna hit them when they carelessly vent these gases into the air. thank goodness that r12 is not quite available now or we would be bathing in UV radiation! hey you did not answer the other part of my post
	() Thanks

24th June 2009, 20:29	#80
anupmathur Senior - BHPian Join Date: Sep 2007 Location: New Delhi Posts: 3,095 Thanked: 307 Times	Ah, the numbers! It would make no sense to quote them for anything other than at the rated capacity. Don't you think so? I am not aware of any defined standards that are followed for quoting car AC compressor performance figures. But that's because this is not my line. I just feel the figures would be for full load operation under some defined ambient temperature conditions and other peripheral equipment that is mated to that compressor.
	() Thanks

24th June 2009, 20:41	#81
eternalck BHPian Join Date: Nov 2008 Location: New Delhi Posts: 175 Thanked: 94 Times	i'm seriously considering buying those gauges. but ebay doesn't have them, do you know where i can get them?
	() Thanks

24th June 2009, 22:05	#83
eternalck BHPian Join Date: Nov 2008 Location: New Delhi Posts: 175 Thanked: 94 Times	actually the problem to go with maruti was that i would have had to spend about 50% of the car's market value! ya you're probably right again that the gauges wouldn't be of much use after just once. so i will just have to approach a 'mechanic' tell him to please follow what i say, and i would give him his fees without him applying his brain on it...
	() Thanks

28th June 2009, 01:52	#84
eternalck BHPian Join Date: Nov 2008 Location: New Delhi Posts: 175 Thanked: 94 Times	i had one mechanic lower the refrigerant, and voila its now chilling like crazy, in the evening when it was 38C outside!! The stationary low side pressure was at 50psi when it was about 42C outside. Naturally when the car would be moving it would come down to about 40psi, nearly the right pressure. Even in the hot sun the coil is extremely cold, the air is cooler than before but the culprit is the hot dash that is making the air hotter as it comes out, i guess a windscreen film would sort that issue out... But the main problem now is that old oil (r12 type) is lying inside the compressor and some new oil was lost when the gas was released into the open air again. So i will have to search for a reputed ac shop and have them disassemble the whole thing and drain that old oil and put new gas in with the oil. But all this can be done next year in the start of the summer. So i have plenty of time to search . Another problem is that still i don't know how much gas goes into the system, maybe the reputed shop'll know about it, or i'll go about with your estimate. But still i can try the same steps as i did this time if nothing works. Thanks all...
	() Thanks

28th June 2009, 10:22	#85
scorpian BHPian Join Date: Jun 2008 Location: GOA Posts: 825 Thanked: 1,219 Times View My Garage	U can get this fixed real cheap...go to any a.c spares shop.buy a tipco compound gauge(75rs),buy two charging lines(80each)and a hand gauge with two openings,with a hand valve(120rs). Now u can check the pressure(running/standing) and do it urself,if you are running 134a please note that the quantity of gas required as compared to r12 is much lower,for example in deep freezers which ran on r12 if the back pressure is kept at 10psi,then the same in r134 is 6psi,a typical thing about 134a is that u need lower gas for it to give u best cooling as compared to r12.This holds very true and i haev seen and personally experienced this many times while working on coldcel freezers,when we would maintain the same pressure as r12 the cooling would be largely inadequate. Since ur based in delhi which has a huge a.c spare part markets u shud get this spares for real duirt cheap,even cheaper then what i have posted the prices...
	() Thanks

28th June 2009, 10:43	#86
eternalck BHPian Join Date: Nov 2008 Location: New Delhi Posts: 175 Thanked: 94 Times	thanks for that info scorpion, i'm probably gonna get those soon now! i am just thinking if it would be harmful for the compressor to operate with lesser oil... but then i think that they probably over filled the oil too by the way scorpian, do you know the amount of gas a can of r134a holds?? and are there newer charging ports (r134a ones) available which could be hooked on to the lines next year when i have it opened up because these older ports have a lot of leakage whenever a hose is being connected to them. and one more thing, these 'mechanics' say that they don't measure the high pressure side cause air would get into the system if they did (!?), another load of cr*p which they speak of . one was even saying that the pressure is the same with both sides!
	() Thanks

29th June 2009, 21:46	#87
scorpian BHPian Join Date: Jun 2008 Location: GOA Posts: 825 Thanked: 1,219 Times View My Garage	Hi, u get ready cans of 134a,made by honeywell and marketed by whirlpool,the can contains 500gms of 134 and is in its purest form which is really great for automoblile use since moisture is a problem when charged from big cylinders,hence the handy can is of great use,the can retails at rs 240/-but like i said earlier since ur based in delhi u will get this spares for dirt cheap since delhi has one of the biggest refriegeration spares market.... For use of 134 u will need couplers to fit on to ur car charging suction line,this again are easily available and u can buy them for as low as 300/- they cum in a pair, high side and a low side,pls be aware charginf from high side is risky,but yes it is absolutely neccessary to check pressures on both side for the best possible cooling, An easier way is to charge the low side and keep checking the mirror on the bottle,also touch the thicker pipe (suction) this should have good sweating on it...if you overfill u will experience not so good cooling as well as ur car running real sluggish,in mpfi vechiles if u overcharge the compressor starts clicking on and off... While charging its a good practise to splash water on the condensor..... Its a very easy process and u will eventually manage it,once ur satisfied with the cooling just note down te pressures so that next time u can just top up incase u run down on gas..
	() Thanks