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Old 9th July 2014, 00:06   #31
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Default Re: Understanding Car Air-Conditioners

you have to keep the jets straight! and at a distance.

I do it all the time no issues.
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Old 9th July 2014, 06:27   #32
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Leop, there are basically two types of automotive air-conditioning systems - Thermal Expansion Valve (TXV) and Clutch Cycling Orifice Tube (CCOT). The Americans automobile manufacturers generally use the latter. I do not know what kind of system your vehicle has since we don't have that particular model with the 1.2 L engine in the US.

In any case, the hissing sound you heard is not that uncommon, it is the sound of the freon expanding as it enters the evaporator. It may be more pronounced when the system is a little low on refrigerant. It does not mean that there is a leak somewhere. On the CCOT systems we have an orifice tube which acts as the restriction for the system and on these systems you can sometimes hear a similar hissing sound after you have switched off the air conditioner and the system is stabilizing (reaching equilibrium).

As far as your situation with the Ford dealership:

1. The line from the condenser to the evaporator is usually a metal line and if the leak was at the valve all they had to do was replace the valve core. Okay, maybe it comes as one piece so you had to bite the bullet on that one.

2. Also, it's a high-pressure line up to the metering device which is either the orifice tube or the expansion valve - so really it's not a suction line at all. Maybe they meant hose section AS6919835AC.

3. 250ml of oil is about 8 ounces. General rule of thumb for AC systems (depending on the size of the system of course) is a couple of ounces of oil in the evaporator, accumulator and condenser and anywhere between 5-10 oz in the compressor. So let's say your compressor takes 5 ounces, the total for the system would be around 8 ounces. Also, it's not compressor oil but refrigerant oil. Compressor oil is what goes in the shop air compressor. lol

4. I think you got taken for a ride for if there was any leak on that line between the condenser and the evaporator you would have seen traces of oil or dye because at that point in the system with the system operational, the Freon is in liquid form . And if there was a small leak, then all you needed to do was add an ounce of oil and probably half a can of Freon.

5. Having a little extra oil in the system will not damage your compressor, but it will reduce the performance. If you want to check if there is excessive oil in the system, without evacuating the whole system, then the best way to do it will be to release some Freon from the low or high side valves after switching off the engine. If you have a lot of oil coming out with the Freon then you may have too much.

I have read some of the posts on this thread ..... there is no charcoal in the accumulator or dryer bottle, it contains a desiccant in pellet or powder form similar to the little silica gel packets one gets with electronics or pharmaceuticals. The charcoal is in the charcoal canister which is part of the evap/fuel system. The recovery/recycle/charging machine does not automatically add oil to the system one has to command it to do so and specify how many ounces. One should not look at the glass window on the dryer bottle to figure out whether the system is fully charged - that was for old R12 systems with mechanical fans. The best way is to look at the pressures - Low and High pressure with engine at idle. If you guys need a chart let me know.

My background is in electrical/electronic engineering but, I also have an AS degree in automotive technology. I did my first automotive air-conditioning system in 1987 when I was still a teen. I like working on AC systems and at this present time and actually fixing the AC on three of my own company vans. I have all the equipment, tools, Freon (even R12) so if anybody needs any help don't hesitate to ask. You can even PM me your phone number and I will call you if need be. {and remember I am on (UTC-05:00) Eastern Time (US & Canada)}

Last edited by Ray32825 : 9th July 2014 at 06:41.
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Old 9th July 2014, 07:43   #33
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Originally Posted by vnabhi View Post
Nice article that got me thinking, but divergent views have got me confused!

While on this, my WagonR will complete 13 years this month end, and is still running on the original AC gas. The AC has never been overhauled this far, but only the fan belt was changed 2 or 3 years back. The AC cools decently, but not as good as the Fords that I bought later.

Is there something I need to overhaul or replace? My annual service was done only a month ago.
Vnabhi, thanks to you I now know what a WagonR is/looks like. It almost looks like a van!

Now, as far as your AC system is concerned, if the compressor and clutch are not making any abnormal noises, I would basically leave it alone. But here are a couple of things that you can check:

1. If the compressor has its own V-belt, make sure that that is not too tight as that would put extra load on an old bearing.

2. Make sure that there is not excessive travel in the clutch plate when it engages - this is measured as an air gap similar to the specs on a spark plug.

3. Have your temperatures and pressures checked to make sure that the system is functioning optimally. If need be add an ounce or two of the recommended refrigerant oil and top up with Freon (it's always better to be slightly on the low side rather than overfill the system)

4. You can also improve the efficiency of your system by cleaning out the blower assembly/evaporator of any leaves and debris that may have collected there over the years. This is done very easily by removing the blower motor and blowing out the dirt with an air nozzle/shop air. If you have any mildew/fungus or dirt in the evaporator coil the best way to disinfected it is to shoot a foam into the evaporator case through the drain pipe. This will get rid of any contaminants on and around the evaporator coil.

5. Since your WagonR is so tall, the volume of air the system needs to circulate is probably much greater than in your Ford. Hence make sure your blower motor is up to the task and if need be get it serviced/lubricated if possible.

6. As suggested earlier in the thread, have you condenser cleaned to ensure proper flow of air. This is done very easily by spraying down the condenser with a mild degreaser and then washing it clean with spray from even a garden hose. If you have access to compressed air I would blow it clean after the wash. This is best done from the opposite direction but that involves removing the fans and sometimes even taking out the radiator (all depends on how much crap you have stuck in the condenser fins).

7. And while you're at it, also make sure that your radiator/AC fans are working properly (on both speeds if a two speed system). If they seem slow have them rebuilt or replaced.

As mentioned in my earlier post to Leop, if you need any help don't hesitate to ask.
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Old 9th July 2014, 10:20   #34
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Originally Posted by vnabhi View Post
The AC cools decently, but not as good as the Fords that I bought later.

Is there something I need to overhaul or replace?
Quote:
Originally Posted by Ray32825 View Post
3. Have your temperatures and pressures checked to make sure that the system is functioning optimally. If need be add an ounce or two of the recommended refrigerant oil and top up with Freon (it's always better to be slightly on the low side rather than overfill the system)
Before you go in for an overhaul, my suggestion would be to check the cooling using a digital probe thermometer (or a kitchen thermometer) for your car and a relatively new Wagon R at the same time and under the same conditions.

Don't race the engine, just insert the probe thermometer into the central vent and record the temperature in your car, vis-a-vis a new car. It should be around 6 C

You can best do this at the maruti A.S.S. - where there is bound to be new cars waiting for first service. If no such luck, with finding a new car, ask the A/C technician to tell you what should be the temperature at the vent - which he can do by looking up the service manual.

If you find that the temperature is higher than what it should be, then it's time you looked at doing a complete flush of the system, and as well as getting the condenser and evaporator cleaned from the outside.

As Ray suggests, I have never seen A/C technicians in India performing the cleaning of these components in-situ. Maybe it's a lack of know-how or lack of access to the kind of tools & cleaning agents he is referring to...
What they normally do, at least in a proper service center (A.S.S.) is as follows:
a) Recover the gas and oil using a recovery machine
b) Remove the evaporator unit from under the dash
c) Remove the condensor from where it sits next to the radiator.
d) Exterior Clean these two components with a jet of water
e) Refit these units back
f) Put in a new cabin air filter (if there's one originally in the setup)
g) Recharge the system , to the desired pressure (psi reading) on high and low sides.

the difference between the A.S.S. and FNG is that the FNG cares two hoots about the environment and will not carry out step a). Rather he will leak it to the atmosphere - lending his might to air pollution.

Last edited by joybhowmik : 9th July 2014 at 10:24.
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Old 9th July 2014, 11:38   #35
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Joy, I did some spring cleaning and took some old compressors out of my garage. I was going to take them to the recycling place and so I dumped them in the back of my old pickup truck. That was months ago, and I never got down to doing it because the pickup truck hasn't been started in years.

Anyway, last weekend I fired up the old pickup truck and guess what, the AC that I did in 1999 still works ice cold! (R12) If the AC system is done properly it should last for years without ever having to be topped up. But most people are not as particular as me, so it is best to run your car's AC system regularly even when it's cold outside.

The O-rings that seal the system are lubricated by the refrigerant oil which is circulated when the system is operational. If you don't run the system for long periods of time the O-rings will dry up, lose their elasticity, and the Freon will leak out. Also remember that the R134 molecule is smaller than the R12 molecule and therefore can escape more easily.

Compressors in the back of my pickup truck -
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Old 9th July 2014, 12:25   #36
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Oh, and as far as AC thermometers are concerned, I have all kinds, even wireless ones, but every vehicle of mine has a mechanical HVAC thermometer stuck in one of the center dash vents and so does my central air conditioning in the house. These are more reliable and rugged compared to their digital counterparts and can be calibrated fairly easily if need be.

If you want to do a performance check on your AC system under normal conditions (not 50C inside the car), it's best to have a set of gauges to monitor the low in high side pressures. But if you don't have any gauges then, with the system set to recycle, you should have an in dash temperature of at least 10C with the blower on three (in a four speed system) and the RPM at 1000.

Thermometer in home AC unit, followed by R134 temperature pressure chart -
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Old 9th July 2014, 12:50   #37
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Recently, I fit the middle row AC blower in my Safari Lx and went for 5000+ Kms long drive to my hometown. In peak of summer the AC used to work quite comfortably during whole journey and it never troubled.

It is while returning just 250 KMs away Bangalore (near Tirupati) suddenly blower stopped blowing air. The blower motor was working as i could make out with noise but no air was coming in blower. Even in night at 9 PM it was very hot outside and we started sweating. I never drive with windows open even in city. I feel it quite uncomfortable due to pollution, noise and air.

I had to stop at that time for some break for 30 minutes as I was driving continuously from Visakhapatnam. After break, when I started again the blower started working little bit but the problem was still there. We reached home around 3 AM.

Next day, when I started car, everything was back to normal. Blower was blowing complete cool air. While searching google, I found out that might be thermostat went wrong, due to this ice crystal forms in cooling coil and in blower. I still have to get it checked due to other higher priorities of work. Will get it checked soon.

This is also one kind of failure one can face even without dirty cooling coil or leaked freon from system.

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Old 9th July 2014, 13:01   #38
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Originally Posted by Ray32825 View Post
If you don't run the system for long periods of time the O-rings will dry up, lose their elasticity, and the Freon will leak out
Absolutely. The key to an effective AC is ensuring the system is run at least once a month. So to those of us in North India, yes- it is important to run the AC even in December.

Quote:
Also remember that the R134 molecule is smaller than the R12 molecule and therefore can escape more easily.
I don't think so. Molecular dimensions are measured in picometres. The average leak hole dimension is several billion times that. The time it takes for refrigerant to leak out of an average leak should not significantly vary.

Quote:
Originally Posted by Ray32825 View Post
These are more reliable and rugged compared to their digital counterparts and can be calibrated fairly easily if need be.
Yes. But availability in India is not as widespread. Many independent workshops (FNG-friendly neighbourhood garage) do not carry them. In main dealerships, it's worse: the challenge is that with huge backlogs, and constant flow of customers, few if any technicians measure the temperature with the thermometers supplied by the car manufacturer. Rather, the 'jugaad' culture of wafting one's fingers around the vent to assess the temperature is unfortunately what happens 99.99% of the time. Unless the customer is knowledgable, and gives hell to everyone in the workshop from General Manager and down to the lowliest staff.

Quote:
Originally Posted by Ray32825 View Post
If you want to do a performance check on your AC system under normal conditions (not 50C inside the car),
You won't believe it. On a recent 1500km run that I did 50C was normal. See measurement on my car's MID below
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Quote:
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it's best to have a set of gauges to monitor the low in high side pressures.
Again difficult to have the DIY tools at home in India - to do these things. But these values are easily measured at the local FNG. Of course whether the readings are really right or not , is a separate issue.
Quote:
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But if you don't have any gauges then, with the system set to recycle, you should have an in dash temperature of at least 10C with the blower on three (in a four speed system) and the RPM at 1000.
10C - for a modern AC is a tad warmer than one would give credit for. IMHO, for mass market cars in India (such as Wagon R)- I have seen vent temperature go to 5C without heavy footing the accelerator. I would probably give a 20% in-efficiency factor due to age/worn-out parts - so that would bring the target temperature to 6C (steady). If however, it tends to be higher than 6C - perhaps 8C or even 10C - then it's surely time for a checkup.

I do wish we had the tools and technology to do the cleanup without dismantling anything at all. There's something to be said for factory finish... and however hard we try, we can never ever succeed in achieving the millimetric precision in re-fitment of parts.
Dash it all... last time I had my A/C serviced - the technician actually thought it prudent to cut the after market reverse camera wire going from the stereo to the rear number plate - all because it was in the way of the evaporator-which he wanted to take out for a thorough clean. It did not occur to him, that he could have created space for the evaporator, by loosening the nuts around the stereo , detaching the camera wire, and then pulling on the evaporator unit. After a few sheeping grins from him as he explained his act, and after I had raised enough hell, to get the GM on the floor, the worker cleaned up after his dastardly act. Now, this happened at one of Toyota's flagship dealers in New Delhi (India's capital) - so you can well imagine what kind of service capabilities exist on the ground!
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Old 9th July 2014, 13:10   #39
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Originally Posted by SS-Traveller View Post
Not really. The most common complaint in car AC systems is loss of cooling, which is equally commonly traced to a choked cooling coil under the dashboard - something like this...
Does this come in all cars? I have a Accent GLE (Petrol)
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Old 9th July 2014, 13:29   #40
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Nice information.
One question regarding the second row AC vents on the MPVs like Ertiga. have noticed that many people (even reviewers) wrote that a certain car has condenser even on second row. But think they are evaporators and not condensers. Is it correct?
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Old 9th July 2014, 14:12   #41
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Nice information.
One question regarding the second row AC vents on the MPVs like Ertiga. have noticed that many people (even reviewers) wrote that a certain car has condenser even on second row. But think they are evaporators and not condensers. Is it correct?
Whenever the coil is inside cabin it is Evaporator coil not Condenser. Condenser coil release heat to outside atmosphere.

Ertiga/Safari has only dual evaporator and rest other parts are shared. Some car used to have dual AC setup. Not sure how they do it. In that case, there may be separate condenser coil for other AC.
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Old 9th July 2014, 14:26   #42
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Originally Posted by anujmishra View Post
Whenever the coil is inside cabin it is Evaporator coil not Condenser. Condenser coil release heat to outside atmosphere.

Ertiga/Safari has only dual evaporator and rest other parts are shared. Some car used to have dual AC setup. Not sure how they do it. In that case, there may be separate condenser coil for other AC.
@Mods, it is good idea to make the corrections in the official reviews, wherever there is a mention of 'Condenser' for the second row. Ex: Ertiga review: http://www.team-bhp.com/forum/offici...ml#post2754065 (Maruti Ertiga : Official Review)
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Old 9th July 2014, 14:27   #43
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Does this come in all cars? I have a Accent GLE (Petrol)
All cars with AC will have a cooling coil (evaporator)

Quote:
Originally Posted by anujmishra View Post
Ertiga/Safari has only dual evaporator and rest other parts are shared. Some car used to have dual AC setup. Not sure how they do it. In that case, there may be separate condenser coil for other AC.
Also the Innova. Innova has a front evaporator (under dash), and a rear evaporator just above the right rear wheel. They share the same refrigerant volume. but the vents for cold air-circulation are isolated.

Last edited by moralfibre : 9th July 2014 at 15:47. Reason: Back to back posts. Please use EDIT / Multi-quote options
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Old 9th July 2014, 15:15   #44
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Also the Innova. Innova has a front evaporator (under dash), and a rear evaporator just above the right rear wheel. They share the same refrigerant volume. but the vents for cold air-circulation are isolated.

I need few clarification regarding Innova A/C

1. Innova have two separate A/C unit, and it can be switched on independently as well. But if i don't switch on the rear A/C why there is water dripping from the second A/C unit above the right rear wheel? i observe this in my Innova. Even if I don't switch on the second A/C I see water dripping from the right rear side. Does this indicate that this unit is ON, even if the switch of second A/C switched off? or the roof mounted switch is only for blower and A/C condenser is controlled from the front? I checked with ASC. But the answer was it is normal and it is like this only

2. How does the Innova ACC works? is the A/C condenser gets switched off when the specified temp is reached or A/C is always on and hot air is mixed to match the required temp? If the later is correct then it is not so optimal?

Can you please explain
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Old 9th July 2014, 15:57   #45
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or the roof mounted switch is only for blower and A/C condenser is controlled from the front?
You seem to have have answered your own question. The A/C compressor is controlled by the A/C button (with a green light)
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2. How does the Innova ACC works? is the A/C condenser gets switched off when the specified temp is reached or A/C is always on and hot air is mixed to match the required temp? If the later is correct then it is not so optimal?
The Y2009 and newer innovas have a fairly early generation design climate control system. You set the temperature using the dash mounted temperature control. Sensors de-activate/activate the compressor when the threshold temperature is reached or exceeded.

I am not certain of what's there in the older innovas - but if it has a mechanical slider control which swings between hot and cold - then it most likely is just controlling the mix of the air from the heater unit with cooled air from the evaporator as it reaches the vents.
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